TW201514315A - Method of preparing pregelatinized, partially hydrolyzed starch and related methods and products - Google Patents

Abstract

Disclosed are methods relating to an extruded pregelatinized, partially hydrolyzed starch prepared by mixing at least water, non-pregelatinized starch, and acid to form a starch precursor. The acid can be a weak acid that substantially avoids chelating calcium ions or a strong acid in a small amount. In the method, pregelatinization and acid-modification of the starch precursor occurs in one step in an extruder. Also disclosed are methods of preparing board using the starch prepared according to the methods, as well as starches and boards prepared by various methods of the invention.

Description

Method for preparing pregelatinized and partially hydrolyzed starch and related methods and products Cross-reference to related applications

This patent application claims US Patent Application No. 14/044,582, filed on Oct. 2, 2013, and International PCT Application No. PCT/US2013/064776, filed on October 14, 2013, and filed on September 23, 2014 The benefit of U.S. Patent Application Serial No. 14/494,547, the entire disclosure of which is hereby incorporated by reference in its entirety in its entirety in its entirety.

Starch generally contains two types of polysaccharides (amylose and amylopectin) and is classified as a carbohydrate. Some starches are pregelatinized, which is usually carried out via a thermal process. In general, the pregelatinized starch can form a dispersion, slurry or gel with cold water. Pregelatinized starch is generally digestible and has been used in a variety of ways, including as an additive to a variety of food products (eg, in baking, snacks, beverages, candies, dairy products, gravy, prepared foods, sauces, and In meat) and in medicine.

Another use of pregelatinized starch is in the preparation of gypsum Siding. In this regard, during the board making process, stucco (ie, gypsum and/or calcium sulphate in the form of calcium sulphate hemihydrate), water, starch and other ingredients are mixed as needed, usually as the term is used for this The technique is carried out in a pin mixer. The slurry is formed and discharged from the mixer to a mobile conveyor with a cover sheet (usually upstream of the mixer) that has been coated with one of the slag coatings (if present). The slurry is spread over the paper (where it may optionally include a slag coating on the paper). Another cover sheet with or without a slag coating is applied to the slurry by, for example, forming a sheet or the like to form a sandwich structure of a desired thickness.

The mixture is cast and hardened to form a solidified (i.e., rehydrated) gypsum by reacting the gypsum gypsum with water to form a matrix of crystalline hydrous gypsum (i.e., calcium sulfate dihydrate). The hydration of the desired gypsum plaster enables the formation of a chain matrix of set gypsum crystals, which in turn imparts strength to the gypsum structure in the product. Residual free (i.e., unreacted) water is removed (e.g., in a kiln) to provide an anhydrous product.

Pregelatinized starch often adds water requirements to the process. In order to compensate for the water demand during manufacture and to make it sufficiently fluid, it is necessary to add water content to the stucco slurry. This excess water produces inefficiencies in manufacturing, including increased drying time, slower manufacturing line speeds, and higher energy costs. The inventors have found that pregelatinized and partially hydrolyzed starch requires less water.

The inventors have also discovered that the techniques for preparing pregelatinized and partially hydrolyzed starch have not been fully satisfactory. Conventional methods for preparing such pregelatinized and partially hydrolyzed starches are not yet effective, their yields are lower and production is slower and energy costs are higher. Therefore, there is a need for improved systems in this technology. A method of pregelatinization and partial hydrolysis of starch, in particular an improved method of exhibiting lower water requirements.

It is to be understood that the inventors have made this background description to assist the reader, and should not be taken as a reference to the prior art, nor should it be considered as indicating that any of the indicated problems are themselves in the art. Understand. Although the described principles may alleviate the problems inherent in other systems in some aspects and embodiments, it should be understood that the scope of the claimed innovations is defined by the scope of the appended claims, and the claimed invention is not The ability to define any specific problem.

In one aspect, the invention provides a method of making a pregelatinized and partially hydrolyzed starch comprising: (a) mixing at least water, non-pregelatinized starch, and substantially avoiding chelation of a weak acid of calcium ions for manufacture a moist starch precursor having a moisture content of from about 8 wt% to about 25 wt%; (b) feeding the wet starch precursor to an extruder; and (c) at about 150 ° C in the extruder The wet starch is pregelatinized and acid modified at a mold temperature of from 300 °F to about 210 °C (about 410 °F). The invention also provides a starch produced according to this method.

In another aspect, the invention provides a method of making a pregelatinized and partially hydrolyzed starch comprising: (a) mixing at least water, non-pregelatinized starch, and a strong acid to produce a moisture content of about 8% by weight Up to about 25% by weight of the wet starch precursor, wherein the amount of the strong acid is about 0.05% by weight or less based on the weight of the starch; (b) feeding the wet starch precursor to the extruder; and (c ) at about 150 ° C (about 300 ° F) to about 210 in the extruder The wet starch is pregelatinized and acid modified at a mold temperature of ° C (about 410 ° F). The invention also provides a starch produced according to this method.

In another aspect, the invention provides a method of making a board comprising: (a) forming a pregelatinized and partially hydrolyzed starch by: (i) mixing at least water, non-pregelatinized starch, and The acid is formed to form a wet starch precursor having a moisture content of from about 8 wt% to about 25 wt%, the acid being selected from the group consisting of: (1) a weak acid that substantially avoids chelation of calcium ions, and (2) An amount of about 0.05% by weight or less by weight of the strong acid of the starch, or (3) any combination thereof; (ii) feeding the wet starch precursor to the extruder; and (iii) having The wet starch is pregelatinized and acid modified in an extruder of a mold at a temperature of about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F); (b) mixing the pregelatinization and Partially hydrolyzed starch and at least water and mortar to form a slurry; (c) disposed between the first cover sheet and the second cover sheet to form a wetted assembly; (d) cutting the wetted assembly Forming the board; and (e) drying the board. In some embodiments, the set gypsum core material has a compressive strength greater than that of a set gypsum core material made using starch prepared in a different manner. In another aspect, the invention provides a panel produced in accordance with this method.

Figure 1 is a continuous viscosity diagram showing the viscosity (left y-axis) and temperature (right y-axis) versus time (x-axis), as shown in Example 2, at 16% by weight moisture content. A gluing profile of the extruded starch wherein the test slurry had a solids content of 10% by weight.

Figure 2 is a continuous viscosity diagram plotting viscosity (left y-axis) and temperature (right y-axis) versus time (x-axis) showing the extrusion at 13% by weight moisture content as illustrated in Example 2. A gluing profile of the starch wherein the test slurry has a solids content of 10% by weight.

Figure 3 is a graph plotting temperature vs. time showing two pre-gelatinized and partially hydrolyzed starch slurries treated as 3% by weight of hydrazine and 0.05, respectively, as set forth in Example 3. Temperature retardation of a third slurry containing a conventional pregelatinized corn starch (having a viscosity of 773 centipoise and an amount of the retarding agent of 0.05% by weight) in a weight percent and 0.0625% by weight of a retarder treatment) (TRS) hydration rate.

Embodiments of the present invention provide methods of making pregelatinized and partially hydrolyzed starch. In one aspect, the invention provides a method of making a sheet, such as a gypsum wallboard. The pregelatinized and partially hydrolyzed starch produced according to the process of the present invention can be used in a variety of other ways, such as in foods (eg, in baked goods, beverages, candies, dairy products, instant puddings, gravy sauces, soup powders, prepared foods). , stuffing, sauces and meat), medicines, feeds, adhesives and colorants. The starches prepared in accordance with some embodiments of the present invention are generally digestible and provide the desired viscosity to the food product and retain most of the functional properties of the original substrate material.

Embodiments of the present invention presuppose, at least in part, the following unexpected and unexpected discovery that the starch is pregelatinized and acid modified in a single step in an extruder. Unexpectedly and unexpectedly, with starch in a separate step Pre-gelling and acid upgrading have considerable advantages in pre-gelling and acid upgrading starch in a single step in an extruder. For example, as described herein, the method of making pregelatinized and partially hydrolyzed starch of the present invention has higher yields, without sacrificing desired properties (eg, viscosity, flow, cold water solubility, etc.) Fast production and lower energy costs.

Additionally, extrusion conditions (e.g., high temperature and pressure) have been found to significantly increase the rate of acid hydrolysis of the starch. Unexpectedly and unexpectedly, this single step process makes it possible to use weak acids such as hydrazine and/or lesser amounts of strong acid for starch acid upgrading. Either acid form provides a mechanism in which the proton-catalyzed hydrolysis of the acid from the acid is carried out. The conventional acid upgrading process includes a purification and neutralization step. According to some embodiments of the invention, the use of a weak acid (e.g., hydrazine) and/or a small amount of a strong acid avoids the need for any neutralization step and subsequent purification steps, which are typically required in conventional systems to purify the starch and by the neutralization step The salt produced.

According to an embodiment of the invention, the extrusion process not only pre-gelatinizes the starch, but also partially hydrolyzes the starch molecules (i.e., via acid modification). Thus the extrusion process in one step provides both physical upgrading (pregelatinization) and chemical upgrading (acid upgrading, partial acid hydrolysis). Pregelatinization provides the starch with the ability to impart strength (e.g., to a final product such as a gypsum board). Acid upgrading advantageously hydrolyzes the starch to provide the starch with the ability to impart strength to the final product, such as gypsum board, and to lower water requirements in the manufacture of the product, such as in the case of a gypsum board manufacturing process. Accordingly, the product of the method of preparing starch according to an embodiment of the present invention is a pregelatinized and partially hydrolyzed starch.

According to some embodiments, the present invention provides an efficient acid upgrading reaction. As described herein, pregelatinization and acid upgrading in an extruder are carried out at elevated temperatures and/or pressures and may result in a rate of acid hydrolysis which may be low temperature (e.g., 50 ° C) and/or low pressure conventional acid. The hydrolysis rate is, for example, approximately 30,000 times or more than 30,000 times. The rate of acid hydrolysis is further increased by increasing the concentration of the reactants by using a low moisture (about 8 wt% to about 25 wt%) content in the starch precursor. Because of this high efficiency of acid upgrading, the inventors have discovered that unexpectedly and unexpectedly, weak acids or very low levels of strong acids can be used in starch precursors to achieve optimal acid upgrading and to avoid neutralization and The need for purification, this neutralization and purification is an expensive, time consuming, and inefficient requirement in conventional systems.

According to some embodiments, the hydrolysis is designed to convert the starch to smaller molecules within the optimal size range, which is defined herein by the desired viscosity of the pregelatinized and partially hydrolyzed starch. If the starch is excessively hydrolyzed, it may be improperly converted into small molecules (such as oligosaccharides or sugars), which in the case of gypsum board may result in a plate strength ratio pregelatinized from the desired viscosity and partially hydrolyzed starch. The board provided is low in strength.

The pregelatinized and partially hydrolyzed starch can be prepared by (i) mixing at least water, non-pregelatinized starch and acid to form a moist starch precursor having a moisture content of from about 8 wt% to about 25 wt%. The acid may be: (1) a weak acid that substantially avoids chelation of calcium ions, (2) a strong acid in an amount of about 0.05% by weight or less based on the weight of the starch, or (3) any combination thereof. The wet starch precursor is pregelatinized and acid modified in one step in an extruder at a higher mold temperature and/or pressure as described herein. The degree of hydrolysis of the starch produces a desired viscosity as described herein, for example.

Thus, in some embodiments, pregelatinized and partially hydrolyzed The powder can be prepared by mixing at least water, non-pregelatinized starch, and substantially avoiding the weak acid of the chelated calcium ion to produce a moist starch precursor having a moisture content of from about 8 wt% to about 25 wt%. The moist starch is then fed into the extruder. The wetted starch is pregelatinized and acid modified to at least partially hydrolyze while at a mold temperature of from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F) in an extruder.

In other embodiments, the pregelatinized and partially hydrolyzed starch can be prepared by mixing at least water, non-pregelatinized starch, and a strong acid to produce a moisture content of from about 8 wt% to about 25 wt% moisture. A starch precursor wherein the amount of the strong acid is about 0.05% by weight or less based on the weight of the starch. The moist starch is then fed into the extruder. The wetted starch is pregelatinized and acid modified to at least partially hydrolyze while at a mold temperature of from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F) in an extruder.

In some embodiments, it is desirable that the resulting pregelatinized and partially hydrolyzed starch be less water-required when included in a stucco slurry, and may be suitable for making panels of good strength (eg, gypsum board). Accordingly, in another aspect, the present invention provides a method of making a gypsum board using starch prepared by the method of the present invention in a single step of pregelatinization and acid upgrading in an extruder. . In some embodiments, the pregelatinized and partially hydrolyzed starch prepared according to embodiments of the present invention has a lower water requirement relative to other pregelatinized starches known in the art.

Thus, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can be included in a stucco slurry having good flow (e.g., into a pin mixer by a feed line). In some embodiments, the A high amount of pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention is because no excess water needs to be added to the system so that even higher strengths and lower plate densities can be achieved. The resulting panels exhibit good strength characteristics (e.g., having good core hardness, tack resistance, compressive strength, etc., or any relationship therebetween based on any combination of values provided herein). Advantageously, doping the starch prepared according to the method of the invention during the manufacture of the gypsum board enables the production of ultra low density products due to increased strength. The gypsum board may be in the form of, for example, gypsum wallboard (often referred to as drywall), which may encompass not only the wall but also the board as understood in the art. However, starch prepared according to this method may have other applications, such as in food products.

Pregelatinization and acid modification

Starch is classified as a carbohydrate and contains two types of polysaccharides, linear and amylopectin. Starch granules are semi-crystalline (as seen, for example, under polarized light) and are insoluble at room temperature. The starch is placed in water and heated ("cooked"), and the crystal structure of the starch granules is melted by the gelation process and the starch molecules are dissolved in water to produce a good dispersion. It has been found that when starch granules are converted to a gelled form, the starch granules initially provide very little viscosity in the water because the starch granules are insoluble in water. As the temperature increases, the starch granules swell and the crystalline structure melts at the gelation temperature. The peak viscosity is achieved when the starch granules are maximally expanded. Further heating will destroy the starch granules and dissolve the starch molecules in the water, and the viscosity will drop abruptly. After cooling, the starch molecules will re-associate to form a 3D gel structure, and the viscosity increases due to the gel structure. Some commercial starches are sold in pregelatinized form, while others are sold in pellet form. According to this issue In some embodiments, in the case of a gypsum board, the particulate form undergoes at least some degree of gelation. To illustrate, in the case of a gypsum board, the starch is pregelatinized (typically in a mixer, pin mixer) prior to being added to the gypsum slurry (also referred to herein as a stucco slurry).

Thus, as used herein, "pregelatinization" means that the starch has any degree of gelation prior to its inclusion in the gypsum slurry or in other applications. In some embodiments associated with gypsum board, the pregelatinized starch may be partially gelled when included in the slurry, but may be changed in the kiln during exposure to elevated temperatures, such as during the drying step of removing excess water. For complete gelation. In some embodiments associated with gypsum board, the pregelatinized starch is not fully gelled even after leaving the kiln, as long as the starch is under such conditions according to the Viscosity Modifying Admixture (VMA) method. It is sufficient to meet the range viscosity characteristics of some embodiments.

Unless otherwise indicated, when viscosity is referred to herein, it is according to the VMA method. According to this method, the viscosity was measured using a Discovery HR-2 Hybrid Rheometer (TA Instruments Ltd) having a concentric cylinder, a standard cup with a vane geometry (diameter 28 mm and length 42.05 mm) 30mm in diameter).

When starch is obtained, differential scanning calorimetry (DSC) techniques are used to determine if the starch is fully gelatinized. The DSC step can be used to observe if the starch is fully gelatinized, for example to confirm that no starch re-agglomeration has occurred. Depending on the temperature required to completely gelatinize the starch, one of two procedures may be employed, as may be appreciated by those skilled in the art, as determined by DSC.

When DSC reveals the full gelation or gelation temperature of the starch Program 1 is used at or below 90 °C. Procedure 2 is used when the gelation temperature is higher than 90 °C. Since the viscosity was measured while the starch was in water, Procedure 2 used a pressurized cooking in a sealed vessel to overheat to a temperature above 100 °C without causing significant evaporation of water. Procedure 1 is reserved for starch that has been fully gelatinized or for starch having a gelation temperature of up to 90 ° C, as gelled in an open system and unable to produce pressurized conditions for gelation, as discussed below Performed in the rheometer. Therefore, the procedure 2 is followed for starch having a higher gelation temperature. In any case, starch (7.5 g, dry) was added to the water to achieve a total weight of 50 g when the viscosity was equivalently measured.

In Procedure 1, the starch was dispersed in water (15% starch by weight of starch and water) and the sample was immediately transferred to a cylindrical chamber. Cover the chamber with aluminum foil. The sample was heated from 25 ° C to 90 ° C at 5 ° C / min and at a shear rate of 200 s ^-1 . The sample was held at 90 ° C for 10 minutes at a shear rate of 200 s ^-1 . The sample was cooled from 90 ° C to 80 ° C at 5 ° C / min and at a shear rate of 200 s ^-1 . The sample was held at 80 ° C for 10 minutes at a shear rate of 0 s ^-1 . The viscosity of the sample was measured at 80 ° C and a shear rate of 100 s ^-1 for 2 minutes. The viscosity is the average of the measured values from 30 seconds to 60 seconds.

Procedure 2 is used to gelatinize starch having a temperature greater than 90 °C. The starch is gelatinized according to methods well known in the starch industry, for example by pressure cooking. The gelled aqueous starch solution (15% of total weight) was immediately transferred to a rheometer measuring cup and equilibrated at 80 ° C for 10 minutes. The viscosity of the sample was measured at 80 ° C and a shear rate of 100 s ^-1 for 2 minutes. The viscosity is the average of the measured values from 30 seconds to 60 seconds.

Viscometer and DSC are two different types of starch gelatinization method. The degree of gelatinization of the starch can be determined by, for example, a thermal analysis chart from DSC, for example using a peak area (melting of crystals) for calculation. Determining the degree of partial gelation does not require a viscosity map (from a viscometer), but it is a good tool for obtaining information such as viscosity change of starch, gelation maximum, gelation temperature, starch back-agulation, retention Viscosity during the period, viscosity at the end of cooling, etc. For the degree of gelation, DSC measurements were carried out in the presence of excess water, especially at or above 67% by weight. If the water content of the starch/water mixture is less than 67%, the gelation temperature will increase as the water content decreases. When the available water is limited, it is difficult to melt the starch crystals. When the water content of the starch/water mixture reaches 67%, the gelation temperature will remain constant no matter how much water is added to the starch/water mixture. The gelation onset temperature indicates the onset temperature of gelation. The gelation end temperature indicates the end of gelation. Gelatinization indicates the amount of crystalline structure that is melted during gelation. The degree of gelation can be indicated by using a enthalpy from the starch DSC thermogram.

Different starches have different gelation initiation temperatures, end temperatures, and gelation enthalpy. Therefore, different starches can become completely gelatinized at different temperatures. It should be understood that when the starch is heated in excess water beyond the end of gelation temperature, the starch is completely gelatinized. In addition, for any particular starch, if the starch is heated below the end of gelation temperature, the starch will partially gelatinize. Thus, partial and incomplete gelation will occur when the starch is heated below the end of gelation in the presence of excess water, as determined, for example, by DSC. When the starch is heated above the end of gelation in the presence of excess water, complete gelation will occur as determined by DSC. The degree of gelation can be adjusted in different ways, such as by heating the starch at a temperature below the end of gelation. Partial gelation occurs. For example, if the starch is completely gelatinized at 4 J/g, when DSC shows that the gelatinization of the starch is only 2 J/g, this means that 50% of the starch has gelatinized. Fully gelatinized starch will not have a DSC thermogram gelation peak when measured by DSC (焓=0J/g)

As indicated, the degree of gelation can be any suitable amount, such as about or above 70%. However, a smaller degree of gelation will make the starch more similar to the granules and may not all achieve the advantages of increased strength, better (more complete) dispersion, and/or reduced water requirements of some embodiments of the present invention. Thus, in some embodiments, it is preferred to have a higher degree of gelation, such as at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97%, at least About 99% or completely (100%) gelatinized. In the case of gypsum board, starch with a lower degree of gelation can be added to the slurry and additional gelation (e.g., up to 100%) occurs in the kiln. For the purpose of adding to the slurry, "complete gelation" is understood to mean fully cooking the starch at or above the gelatinization temperature of the starch or otherwise making the starch completely visible as visible from DSC technology. Chemical. Although some small degree of starch back-agulation can be expected after cooling, for addition to gypsum slurry or for other applications, in some embodiments, as will be recognized by those of ordinary skill in the art, starch will still be understood as "Complete gelation". In contrast, for the purpose of the VMA method discussed herein, the starch re-aggregation is not accepted in performing the viscosity measurement.

The starch molecules can be acid modified to, for example, hydrolyze glycosidic linkages between glucose units to achieve the desired molecular weight. One benefit of upgrading starch acid to achieve molecular weight reduction is that the water demand will decrease. Conventional pregelatinized starch without acid modification has a very high water requirement, which is associated with higher energy costs. Learning It is conventionally believed that upgrading is generally preferred prior to gelation because it tends to be more efficient and less cost intensive. Unexpectedly and unexpectedly, however, the inventors have discovered that pregelatinization and acid upgrading can be incorporated into a single step such that they can be carried out simultaneously rather than one by one.

Method for preparing starch

According to some embodiments of the invention, a moist starch precursor is prepared prior to entering the extruder. The wet starch precursor can be prepared by any suitable method. For example, in some embodiments, the wet starch precursor is prepared by adding water and an acid to the starch material, which is (a) substantially avoiding the weak acid of the chelated calcium ion and/or (b) a small amount strong acid.

Any suitable starch material can be selected to prepare the wet starch precursor as long as it can be used to make a pregelatinized and partially hydrolyzed starch, such as a starch material that meets the mid-range viscosity characteristics of some embodiments of the present invention. As used herein, "starch" refers to a composition comprising a starch component. Thus, the starch may be 100% pure starch or may have other components, such as those commonly found in flour, such as proteins and fibers, so long as the starch component constitutes at least about 75% by weight of the starch composition. . The starch may be in the form of a flour containing starch (e.g., corn flour), such as flour having at least about 75% (e.g., at least about 80%, at least about 85%, at least about 90%, at least about 95%, etc.) starch by weight of the flour. . Any suitable unmodified starch or flour can be used to prepare the precursor of the pregelatinized and partially hydrolyzed starch of the present invention. For example, the starch may be CCM260 yellow corn meal, CCF600 yellow corn flour (Bunge North America), Clinton 106 (ADM), and/or Midsol 50 (MGP) Ingredients).

The wet starch precursor can be prepared to have any suitable moisture content to achieve the desired pregelatinization and acid upgrading levels in the extruder. For example, in some embodiments, the moisture content of the wet starch precursor needs to be from about 8 weight percent to about 25 weight percent, based on the total weight of the starch precursor, such as about 8 percent by total weight of the wet starch precursor. % by weight to about 23% by weight, such as about 8% by weight, about 21% by weight, about 8% by weight, about 20% by weight, about 8% by weight, about 19% by weight, about 8% by weight, about 18% by weight, about 8% by weight to About 17% by weight, about 8% by weight to about 16% by weight, about 8% by weight to about 15% by weight, about 9% by weight to about 25% by weight, about 9% by weight to about 23% by weight, and about 9% by weight to About 21% by weight, about 9% by weight to about 20% by weight, about 9% by weight to about 19% by weight, about 9% by weight to about 18% by weight, about 9% by weight to about 17% by weight, and about 9% by weight to About 16% by weight, about 9% by weight to about 15% by weight, about 10% by weight to about 25% by weight, about 10% by weight to about 23% by weight, about 10% by weight to about 21% by weight, about 10% by weight to About 20% by weight, about 10% by weight to about 19% by weight, about 10% by weight to about 18% by weight, about 10% by weight to about 17% by weight, about 10% by weight to about 16% by weight, about 10% by weight to About 15% by weight, about 11% by weight to about 25% by weight, about 11% by weight, about 2% 3 wt%, from about 11 wt% to about 21 wt%, from about 11 wt% to about 20 wt%, from about 11 wt% to about 19 wt%, from about 11 wt% to about 18 wt%, from about 11 wt% to about 17% by weight, about 11% by weight to about 16% by weight, about 11% by weight to about 15% by weight, about 12% by weight to about 25% by weight, about 12% by weight to about 23% by weight, about 12% by weight to about 21% by weight, about 12% by weight to about 20% by weight, about 12% by weight to about 19% by weight, From about 12% to about 18% by weight, from about 12% to about 17% by weight, from about 12% to about 16% by weight, from about 12% to about 15% by weight, from about 13% to about 25% by weight, From about 13% by weight to about 23% by weight, from about 13% by weight to about 21% by weight, from about 13% by weight to about 20% by weight, from about 13% by weight to about 19% by weight, from about 13% by weight to about 18% by weight, From about 13% by weight to about 17% by weight, from about 13% by weight to about 16% by weight, from about 13% by weight to about 15% by weight, from about 14% by weight to about 25% by weight, from about 14% by weight to about 23% by weight, From about 14% by weight to about 21% by weight, from about 14% by weight to about 20% by weight, from about 14% by weight to about 19% by weight, from about 14% by weight to about 18% by weight, from about 14% by weight to about 17% by weight, From about 14% by weight to about 16% by weight or from about 14% by weight to about 15% by weight. It should be understood that when preparing a moist starch, the moisture content described herein includes ambient moisture and added water.

While not wishing to be bound by any particular theory, it is believed that the lower moisture content causes greater friction in the extruder. In some embodiments, the moisture content can be prepared to allow the wetting starch to have sufficient mechanical energy input when fed through the extruder such that the friction prevents the wetting starch from moving too easily through the extruder. Increased friction can increase the destruction of hydrogen bonds in the starch.

Any suitable weak acid that substantially avoids chelation of calcium ions can be mixed into the moist starch. Without wishing to be bound by any particular theory, the chelating includes a weak acid such as a coordination complex with calcium or otherwise interferes with gypsum crystal formation within the gypsum slurry. Such interference can be to reduce the number of gypsum crystals formed, delay the formation of crystals (to reduce their rate), reduce interaction between gypsum crystals, and the like. The term "substantially" with respect to non-chelating calcium ions generally means at least 90% (eg, at least 92%, at least 95%, at least 96%, to Less than 97%, at least 98% or at least 99% of the available calcium ions do not chelate with the acid.

A weak acid according to an embodiment of the invention may be defined as having a pKa value of from about 1 to about 6, such as from about 1 to about 5, from about 1 to 4, from about 1 to 3, from about 1 to 2, from about 1.2 to about 6, and about 1.2. Up to about 5, from about 1.2 to about 4, from about 1.2 to about 3, from about 1.2 to about 2, from about 2 to about 6, from about 2 to about 5, from about 2 to about 4, from about 2 to about 3, from about 3 to about 6. A weak acid of from about 3 to about 5, from about 3 to about 4, from about 4 to about 6, or from about 4 to about 5. As understood in the art, the pKa value is a measure of acid strength; the lower the pKa value, the stronger the acid.

A weak acid that substantially avoids chelation of calcium ions is characterized, for example, by the lack of multiple binding sites, such as a plurality of carboxyl functional groups (COO-) that tend to bind calcium ions. In some embodiments, the amount of a weak acid binding site (such as a poly-COO- group) is minimal, or substantially free of multiple binding sites (such as a poly-COO- group) such that, for example, chelation is minimal ( That is, substantially avoided) or the formation of gypsum crystals is substantially immune to impact relative to crystals formed in the absence of a weak acid. In some embodiments, for example, aluminum sulfate (矾) is a suitable weak acid for the preparation of wet starch because it substantially avoids chelation of calcium ions.矾 does not have multiple binding sites.

In some embodiments, the mash is added to the wet starch precursor in any suitable form, such as in the form of a liquid containing the desired solids content. For example, liquid helium can be included in an aqueous solution wherein the helium is present in any suitable amount. Other weak acids can be similarly added.

The moist starch may be mixed to include any suitable amount of a weak acid that substantially avoids chelation of calcium ions, such that the pregelatinized portion is prepared and partially Hydrolyzed starch has the desired viscosity and lower water requirement and is not excessively hydrolyzed to sugar. For example, in some embodiments, the weak acid is included in an amount from about 0.5% to about 5% by weight, based on the weight of the starch, such as from about 0.5% to about 4.5% by weight, such as from about 0.5% to about 4% by weight. %, from about 0.5% by weight to about 3.5% by weight, from about 0.5% by weight to about 3% by weight, from about 1% by weight to about 5% by weight, from about 1% by weight to about 4.5% by weight, from about 1% by weight to about 4% by weight %, from about 1% by weight to about 3.5% by weight, from about 1% by weight to about 3% by weight, from about 1.5% by weight to about 5% by weight, from about 1.5% by weight to about 4.5% by weight, from about 1.5% by weight to about 4% by weight %, from about 1.5% to about 3.5% by weight, from about 1.5% to about 3% by weight, from about 2% to about 5% by weight, from about 2% to about 4.5% by weight, from about 2% to about 4% by weight %, from about 2% by weight to about 3.5% by weight, from about 2% by weight to about 3% by weight, from about 2.5% by weight to about 5% by weight, from about 2.5% by weight to about 4.5% by weight, from about 2.5% by weight to about 4% by weight %, from about 2.5% to about 3.5% by weight or from about 2.5% to about 3% by weight. It should be understood that such amounts encompass the weak acid component and do not include water or other components of the solution when the weak acid is in solution.

The moist starch precursor can be prepared to further comprise a secondary acid that can chelate calcium ions, such as tartaric acid, as appropriate. Thus in some embodiments, a secondary acid such as tartaric acid can be combined with any suitable weak acid that does not chelate calcium ions. Tartaric acid is known to delay the crystallization of gypsum. However, in combination with a non-chelating weak acid, tartaric acid avoids substantial delay in the crystallization of the gypsum, optimizing the hydrolysis reaction via acid upgrading. In addition to tartaric acid, other secondary acids such as succinic acid or malic acid may be beneficial as long as they do not exceed the accelerated effect of hydrazine. In some embodiments, the moist starch precursor includes both strontium and tartaric acid.

If included, the secondary acid (e.g., tartaric acid) can be present in any suitable amount. For example, tartaric acid can be present in an amount from about 0.1% to about 0.6% by weight, such as from about 0.1% to about 0.4% by weight, from about 0.2% to about 0.3% by weight, based on the weight of the starch.

In some embodiments, oil may be added to the moist starch as appropriate to improve the transportability of the starch within the extruder. In some embodiments, possible oils include rapeseed oil, vegetable oil, corn oil, soybean oil, or any combination thereof. For example, in some embodiments, rapeseed oil or one of the foregoing alternatives may optionally be added in an amount from about 0% to about 0.25% by weight, such as from about 0.1% to about 0.2% by weight, based on the weight of the starch, From about 0.1% to about 0.15% by weight, from about 0.15% to about 0.25% by weight, from about 0.15% to about 0.2% by weight, or from about 0.2% to about 0.25% by weight.

According to some embodiments, the wet starch precursor is prepared by mixing water, non-pregelatinized starch, and a small amount of strong acid. In some embodiments, the strong acid has a pKa of about -1.7 or -1.7 or less. Any such strong acid can be used, and in some embodiments, the strong acid comprises sulfuric acid, nitric acid, hydrochloric acid, or any combination thereof. In some embodiments, sulfuric acid alone or in combination with other acids is preferred because sulfate ions accelerate gypsum crystallization in the gypsum board embodiment.

The amount of strong acid is relatively small, such as about 0.05% by weight or less by weight based on the weight of the starch, such as about 0.045% by weight or 0.045% by weight, based on the weight of the starch, about 0.04% by weight or less, and about 0.035% by weight. % or 0.035 wt% or less, about 0.03 wt% or 0.03 wt% or less, about 0.02 wt% or 0.02 wt% or less, about 0.02 wt% or less or less than 0.02 wt%, about 0.015 wt% or 0.015 wt% or less, about 0.01% by weight or less, less than 0.005% by weight or 0.005% by weight, less than 0.001% by weight or less than 0.001% by weight, about 0.0005% by weight or less than 0.0005% by weight, such as from about 0.0001% by weight to about 0.05% by weight, From about 0.0001% by weight to about 0.045% by weight, from about 0.0001% by weight to about 0.04% by weight, from about 0.0001% by weight to about 0.035% by weight, from about 0.0001% by weight to about 0.03% by weight, from about 0.0001% by weight to about 0.025% by weight, From about 0.0001% by weight to about 0.02% by weight, from about 0.0001% by weight to about 0.015% by weight, from about 0.0001% by weight to about 0.01% by weight, from about 0.0001% by weight to about 0.005% by weight, from about 0.0001% by weight to about 0.001% by weight %, from about 0.0001% by weight to about 0.0005% by weight. It should be understood that such amounts encompass the strong acid component and do not include water or other components of the solution when the strong acid is in solution. For example, conventional strong acid upgrading uses a 2% sulfuric acid solution with about 35% starch solids (2 g sulfuric acid for 35 g starch). The percentage is based on the pure sulfuric acid component. Calculated by dividing the weight of the sulfuric acid component by the weight of the moist starch. For example, if the sulfuric acid is 50% pure (which means that one-half of the weight of the solution is pure sulfuric acid), the weight of the sulfuric acid solution is doubled. To illustrate, 0.1 g of pure sulfuric acid was added to 100 g of starch to achieve 0.1% by weight. If the concentration of the sulfuric acid solution is 50%, 0.2 g of a 50% sulfuric acid solution is added to achieve 0.1% by weight.

It should be understood that there are different grades of acid (>95%, 98%, 99.99%). These differences are covered by the term "about" and relate to the amount of strong acid in the starch precursor. Those skilled in the art will readily be able to determine the weight % described herein to include different grades. The amount of strong acid used in accordance with some embodiments of the present invention is significantly less than the amount of strong acid included in conventional systems that use, for example, at least about 2 grams of sulfuric acid to 35 grams of starch. In some embodiments, as described above A small amount of strong acid can be used in combination with a weak acid such as hydrazine which does not chelate calcium ions as described herein.

Embodiments of the present invention provide for feeding a wet starch precursor through an extruder to pregelatinize and acid modify the wet starch precursor in a single step in an extruder. It will be appreciated that the extruder is a machine typically used to melt the polymer and pump it into a desired shape by melting the polymer and pumping it through a die. The extruder can also mix the polymer with other ingredients such as pigments, reinforcing fibers, inorganic fillers and the like. The purpose of the extruder is to disperse and distribute all of the components fed therein and to melt the components at a constant temperature and pressure.

The configuration and configuration of the extruder is known in the art. In general, an extruder includes a feed hopper (which transfers the material fed in), a pre-regulator (which includes a heating jacket for conditioning the polymer and a plasticizer (eg, water)), and an extruder head ( It contains a heating zone) and a mold assembly. The extruder generally includes a feed auger, a hob and one or more screws. There is a feed auger to help transport the wet starch precursor to the extruder. There is a hob to pre-gelatinize the chain and the partially hydrolyzed starch is cut into smaller pellets so that it can be ground. The screw assists in mixing the wet starch precursor, transporting the wet starch precursor through an extruder and providing mechanical shear. As will be understood by those of ordinary skill in the art, the extruder can be a single or twin screw variety. See, e.g. Leszek Moscicki, Extrusion-Cooking Techniques, WILEY-VCH Verlag & Co.KGaA, 2011.

In a single screw extruder, the screw generally comprises a feed zone (having a deep passage for conveying solids from the feeder inlet and compressing the solids), a compression section (where the screw passage is gradually shallower) And the polymer melts) And a quantitative portion (which has a shallow channel for transporting the molten polymer into the mold). Some screws are designed to include a mixing device (eg, a pin extending from the screw).

Twin screw extruders typically have two screws that rotate in the same direction (i.e., co-rotate) or rotate in opposite directions (i.e., reverse rotation). The two screws can be rotated without the stagger being staggered or completely staggered. Although in the case of a single screw extruder, the fed material fills the entire screw passage, in the case of a twin screw extruder, only one part of the screw passage is filled so that the downstream feed port or discharge port can be used Add some ingredients.

The mold assembly typically includes a sheet, a spacer, and a die. When extruding the material, the process can be continuous to allow the material to be extruded in an indefinite length, or semi-continuous to allow the material to be extruded in multiple sheets. The extruded material can be hot or cold.

The present invention provides a process for preparing a pregelatinized and partially hydrolyzed starch in an extruder. Any suitable extruder may be used, such as a single screw extruder (e.g., Advantage 50 available from American Extrusion International, South Beloit, IL) or a twin screw extruder (e.g., from Wenger, Sabetha, KS) Purchased Wenger TX52).

As described herein, the non-pregelatinized starch, the acid in the form of a weak acid that substantially avoids chelation of calcium ions, and/or a relatively small amount of strong acid form, and water are mixed and fed into the extruder. In some embodiments, additional water can be added to the extruder. When in the extruder, the combination of heating element and mechanical shear causes the starch to melt and pregelatinize, and the weak acid causes the starch to be partially hydrolyzed as desired to the desired molecular weight as indicated by viscosity. Because of mechanical energy, the conditions in the extruder It will also cause degradation of starch molecules, which partially produces the same effect of acid upgrading. According to some embodiments, a weak acid and/or a lower amount of a strong acid can be used because conditions in the extruder (e.g., high reaction temperature and high pressure) promote the chemical reaction. Thus, the method of the invention improves the efficiency of starch acid upgrading.

The main screw can be operated at any suitable speed to achieve the desired mixing and mechanical shearing. For example, in some embodiments, the main screw can operate at a speed of about 350 RPM (± about 100 revolutions). The feed auger can be operated at any suitable speed to achieve the desired feed rate. For example, in some embodiments. The feed auger can operate at a speed of about 14 RPM (± about 5 RPM).

The hob can operate at any suitable speed. For example, in various embodiments, the hob can operate at a speed of from about 400 RPM to about 1,000 RPM, such as from about 400 RPM to about 900 RPM, from about 400 RPM to about 800 RPM, from about 400 RPM to about 700 RPM, from about 400 RPM to about 600 RPM, about 400 RPM. Up to about 500 RPM, from about 500 RPM to about 1,000 RPM, from about 500 RPM to about 900 RPM, from about 500 RPM to about 800 RPM, from about 500 RPM to about 700 RPM, from about 500 RPM to about 600 RPM, from about 600 RPM to about 1,000 RPM, from about 600 RPM to about 900 RPM, about 600 RPM. To about 800 RPM, from about 600 RPM to about 700 RPM, from about 700 RPM to about 1,000 RPM, from about 700 RPM to about 900 RPM, from about 700 RPM to about 800 RPM, from about 800 RPM to about 1,000 RPM, from about 800 RPM to about 900 RPM, or from about 900 RPM to about 1,000 RPM.

Wet starch can be pregelatinized and acid modified in an extruder having a mold at any suitable temperature so that the moist starch does not In the case of burning of the material, it becomes sufficient to be pregelatinized. For example, the moist starch can be pregelatinized and acid modified in an extruder having a mold at a temperature of from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F), such as in various implementations. In particular, from about 150 ° C to about 205 ° C (about 400 ° F), from about 150 ° C to about 199 ° C (about 390 ° F), from about 150 ° C to about 193 ° C (about 380 ° F), from about 150 ° C to about 188 ° C ( About 370 °F), about 150 ° C to about 182 ° C (about 360 ° F), about 154 ° C (about 310 ° F) to about 210 ° C, about 154 ° C to about 205 ° C (about 400 ° F), about 154 ° C to about 199 °C, from about 154 ° C to about 193 ° C, from about 154 ° C to about 188 ° C, from about 154 ° C to about 182 ° C, from about 160 ° C (about 320 ° F) to about 210 ° C, from about 160 ° C to about 205 ° C (about 400 ° F ), from about 160 ° C to about 199 ° C, from about 160 ° C to about 193 ° C, from about 160 ° C to about 188 ° C, from about 160 ° C to about 182 ° C, from about 166 ° C (about 330 ° F) to about 210 ° C, about 166 ° C To about 205 ° C, about 166 ° C to about 199 ° C, about 166 ° C to about 193 ° C, about 166 ° C to about 188 ° C, about 166 ° C to about 182 ° C, about 171 ° C (about 340 ° F) to about 210 ° C, From about 171 ° C to about 205 ° C, from about 171 ° C to about 199 ° C, from about 171 ° C to about 193 ° C, from about 171 ° C to about 188 ° C, from about 171 ° C to about 182 ° C, 177 ° C (about 350 ° F) to about 210 ° C, about 177 ° C to about 205 ° C, about 177 ° C to about 199 ° C, about 177 ° C to about 193 ° C, about 177 ° C to about 188 ° C or about 177 ° C to about 182 °C. While the mold of the extruder can be any sufficient temperature as described herein, the mold temperature generally exceeds the melting temperature of the starch crystals.

The degree of gelation can be any suitable amount, such as at least about 70% or more, such as at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 97. %, at least about 99% or completely (100%) gelatinized. In the case of manufacturing a siding as described below, it can be ash Starch having such a lower degree of gelation is added to the mud slurry and additional gelation (e.g., up to 100%) occurs, for example, in the kiln.

The pressure in the extruder can be at any suitable level to achieve the proper conditions for pregelatinization and acid upgrading. The pressure inside the extruder is determined by the extruded material, moisture content, mold temperature and screw speed that will be recognized by those skilled in the art. For example, the pressure in the extruder can be at least about 2,000 psi (about 13,800 kPa), such as at least about 2,250 psi (about 15,500 kPa), at least about 2,500 psi (about 17,200 kPa), at least about 2,750 psi (about 19,000). kPa), at least about 3,000 psi (about 20,650 kPa), at least about 3,500 psi (about 24,100 kPa), at least about 4,000 psi (about 27,600 kPa), or at least about 4,500 psi (about 31,000 kPa). In some embodiments, the pressure can range from about 2,000 psi to about 5,000 psi (34,500 kPa), such as from about 2,000 psi to about 4,500 psi, from about 2,000 psi to about 4,000 psi, from about 2,000 psi to about 3,500 psi, from about 2,000 psi to about 3,000 psi. From about 2,000 psi to about 2,500 psi, from about 2,500 psi to about 5,000 psi, from about 2,500 psi to about 4,500 psi, from about 2,500 psi to about 4,000 psi, from about 2,500 psi to about 3,500 psi, from about 2,500 psi to about 3,000 psi, from about 3,000 psi to about 5,000 psi. 3,000 psi to about 4,500 psi, about 3,000 psi to about 4,000 psi, about 3,000 psi to about 3,500 psi, about 3,500 psi to about 5,000 psi, about 4,000 psi to about 5,000 psi, about 4,000 psi to about 4,500 psi, or about 4,500 psi to about 5,000 psi.

Unexpectedly and unexpectedly, it has been found that the process of the present invention for preparing pregelatinized and partially hydrolyzed starch in a single step in an extruder prior to pre-gelling and acid upgrading the starch in two successive steps Much faster. The amount of pregelatinized and partially hydrolyzed starch prepared by the method of the present invention is compared with any other method The amount of starch prepared is much larger. Higher throughput and faster yield rates are due to high reaction rates at elevated temperatures and/or high pressures. In some embodiments, the pregelatinization and acid upgrading are carried out in less than about 5 minutes, such as less than about 4 minutes, such as less than about 3 minutes, less than about 2 minutes, less than about 90 seconds, less than about 75 seconds, less than About 1 minute, less than about 45 seconds, less than about 30 seconds, less than about 25 seconds, less than about 20 seconds, less than about 15 seconds, or less than about 10 seconds. Additionally, in some embodiments, pregelatinization and acid upgrading are carried out in the extruder at a rate that is bound by any two of the foregoing. For example, the pregelatinization and acid upgrading rates can be between about 10 seconds and 5 minutes, such as between about 10 seconds and about 4 minutes, between about 10 seconds and about 3 minutes, at about 10 Between seconds and about 2 minutes, between about 10 seconds and about 90 seconds, between about 10 seconds and about 75 seconds, between about 10 seconds and about 1 minute, between about 10 seconds and about 45 seconds Between about 10 seconds and about 30 seconds, between about 10 seconds and about 25 seconds, between about 10 seconds and about 20 seconds, or between about 10 seconds and about 15 seconds.

The process of the present invention for preparing pregelatinized and partially hydrolyzed starch can be a continuous process carried out at any sufficient rate. In some embodiments, the starch is pregelatinized and acid modified in an extruder at a rate of production of at least about 100 kg/hr, such as at least about 150 kg/hr, at least about 200 kg/hr, at least about 250 kg/ Hr, at least about 300 kg/hr, at least about 350 kg/hr, at least about 400 kg/hr, at least about 450 kg/hr, 500 kg/hr, at least about 550 kg/hr, such as at least about 600 kg/hr, at least about 650 kg/hr, at least About 700 kg/hr, at least about 750 kg/hr, at least about 800 kg/hr, at least about 850 kg/hr, at least about 900 kg/hr, at least about 950 kg/hr, at least about 1,000 kg/hr, at least about 1,050 kg/hr, at least About 1,100 kg/hr, at least about 1,150 kg/hr, at least about 1,200 Kg/hr, at least about 1,250 kg/hr, at least about 1,300 kg/hr, at least about 1,350 kg/hr, at least about 1,400 kg/hr, at least about 1,450 kg/hr, or at least about 1,500 kg/hr. Additionally, in some embodiments, the rate of production yield in the extruder can be limited by any two of the foregoing. For example, the production yield rate can be between about 100 kg/hr and about 1,500 kg/hr (eg, between about 100 kg/hr and about 1,500 kg/hr, between about 100 kg/hr and 1,000 kg/hr). Between about 250 kg/hr and about 1,500 kg/hr, between about 250 kg/hr and about 1,000 kg/hr, between about 600 kg/hr and about 1,250 kg/hr, at about 650 kg/hr and about Between 1,200 kg/hr, between about 700 kg/hr and about 1,100 kg/hr, between about 750 kg/hr and about 1,000 kg/hr, etc.).

The inventors have found that in some embodiments, the conditions in the extruder (e.g., high temperature and pressure) are particularly advantageous for pre-gelling and acid upgrading of the starch in a single step. When the extruder mixes the wet starch, it produces extremely high friction, which in turn generates heat. Since the space between the screw and the chamber in the extruder is extremely small, shear force is generated by the screw in the extruder. The mechanical energy of the target per unit mass is described in terms of mechanical energy (SME). SME will depend on the moisture content. Higher moisture content (for example for fluidity purposes) will result in low viscosity and low friction, and thus in smaller SMEs. If there is more water, it will produce a smaller SME due to low viscosity and low friction. The moisture content of the moist starch precursor of the present invention as described herein provides an effective SME.

In the extruder, the starch is pre-gelatinized highly efficiently because of the conditions provided by the examples of the invention as described herein. Without wishing to be bound by any particular theory, the water required for good mixing in an extruder in accordance with some embodiments of the present invention is more water than is required to react in an extruder. less. The extremely low moisture content promotes a high concentration of the reactants which accelerates the rate of chemical reactions. The high temperature of the extruder also significantly accelerates the reaction rate. As the starch leaves the extruder, the reaction takes place such that it is pregelatinized and partially hydrolyzed.

In conventional acid upgrading, starch is added to a strong acid solution. The water and acid used in this conventional method are used in the unexpected and unexpected methods of pre-gelling and acid-modifying starch in a single step, rather than continuously, in an extruder in an extruder as described herein. There is much more water. It takes several hours for the acid to be modified. After the reaction has taken place, it is necessary to neutralize the acid, purify and wash away. Neutralization and purification steps are time consuming and expensive.

Until the unexpected and unexpected discovery by the inventors, it is considered unnecessary in the conventional acid upgrading that it is a weak acid or a relatively small amount of a strong acid which substantially avoids chelation of calcium ions. This is because in the conventional method, the weaker the acid is, the smaller the amount of strong acid is, and the longer the acid reforming takes. Thus, in conventional acid upgrading, high amounts of strong acid are required (e.g., a pKa is less than about -1.7). Unexpectedly and unexpectedly, when a pre-gelatinized and partially hydrolyzed starch is prepared in an extruder in accordance with an embodiment of the invention using a weak acid or a relatively small amount of a strong acid as described herein, the acidic conditions are mild and Gypsum crystals have less interference and do not require neutralization and purification steps. In some embodiments, the acid may still be present in the pregelatinized and partially hydrolyzed starch.

Starch characteristics and advantages of using the starch in gypsum board

The starch prepared in the extruder according to an embodiment of the invention may be any pregelatinized and partially hydrolyzed starch. In some embodiments, as described herein, the starch produced can have various characteristics as desired (eg, medium range viscosity) Degree, cold water solubility, cold water viscosity, etc.).

The pregelatinized and partially hydrolyzed starch prepared in an extruder according to an embodiment of the present invention can be applied to a gypsum board. For example, as described herein, in accordance with embodiments of the present invention, pregelatinization and acid upgrading are beneficial for applications in gypsum board, such as achieving the desired viscosity for strength purposes (and thus achieving Molecular weight range). In the method of making a siding as discussed herein, the starch introduced into the stucco slurry can be at least about 70% gelatinized, such as at least about 75% gelatinized, at least about 80% gelatinized, at least about 85% gelatinized. Condensation, at least about 90% gelation, at least about 95% gelation, at least about 97% gelation, or 100% gelation (ie, complete gelation).

Furthermore, the wetting of a starch comprising a weak acid substantially avoiding chelation of calcium ions as described herein is fed to an extruder to hydrolyze the starch to achieve the desired viscosity, thus indicating that the desired molecular weight is achieved, in accordance with an embodiment of the present invention. range. As will be appreciated by those of ordinary skill in the art, the viscosity, in turn, indicates the molecular weight of the pregelatinized and partially hydrolyzed starch.

In some embodiments, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can be prepared to have any suitable viscosity. In some embodiments, when the pregelatinized and partially hydrolyzed starch is subjected to water in an amount according to which the pregelatinized and partially hydrolyzed starch is 15% by weight based on the pregelatinized and partially hydrolyzed starch and total weight of water The viscosity of the VMA method is characterized by a "medium range" viscosity (i.e., a viscosity of from about 20 centipoise to about 700 centipoise). Thus, the VMA method was used to determine whether the pregelatinized and partially hydrolyzed starch exhibited a mid-range viscosity characteristic when subjected to the conditions of the VMA method. This does not mean pre-gelatinized and partially hydrolyzed starch must be added to the gypsum slurry under these conditions. In the material. Conversely, when a pregelatinized and partially hydrolyzed starch is added to the slurry, it may be in a wet form (in various concentrations of aqueous starch solution) or an anhydrous form, and it need not be fully gelatinized as described herein or It is otherwise under the conditions set forth in the VMA method.

In some embodiments, the pre-gelatinized starch may have a range viscosity of from about 20 centipoise to about 700 centipoise, such as from about 20 centipoise to about 500 centipoise, from about 30 centipoise to about 200 centipoise or about 100. From centipoise to about 700 centipoise. In the examples of the present invention, the viscosity of the pregelatinized starch when tested under the VMA method can be exemplified as listed in Tables 1A, 1B and 1C below. In these tables, "X" indicates the range "about [corresponding value in the top column] to about [corresponding value in the leftmost column]". The indicated value indicates the viscosity of the pregelatinized starch in centipoise. For ease of presentation, each value indicates "about" the value. For example, the first "X" in Table 1A is in the range "about 20 centipoise to about 25 centipoise".

Thus, the pregelatinized and partially hydrolyzed starch prepared according to embodiments of the present invention may have a viscosity range between any of the aforementioned endpoints set forth in Tables 1A, 1B or 1C and include any of them. . Alternatively, in some embodiments, the pregelatinized and partially hydrolyzed starch has a viscosity (10% solids, 93 ° C) of about 5 Brabant as measured by the Brabender method described herein. The unit (BU) is up to about 33 BU, for example from about 10 BU to about 30 BU, from about 12 BU to about 25 BU or from about 15 BU to about 20 BU.

In some embodiments, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can provide significant benefits to the strength of the product to which it is applied, such as a siding. Since starch contains a glucose monomer containing three hydroxyl groups, starch provides a number of sites for forming hydrogen bonds with gypsum crystals. Without wishing to be bound by any particular theory, it is believed that the molecular size of the pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention allows for optimal migration of starch molecules aligned with starch molecules and gypsum crystals, To promote good bonding of the starch to the gypsum crystals, the resulting crystalline gypsum matrix is reinforced, for example, via hydrogen bonding.

Conventional pregelatinized starches prepared according to another method different from the methods described herein, for example, having a viscosity outside the middle range will have a longer chain length and a higher molecular weight (too much viscosity) and a shorter chain length, respectively. Lower molecular weight (too low viscosity) does not provide the same combination of benefits. It is also believed that with regard to starch efficiency, when the starch molecules are sufficiently combined with the gypsum crystals, the additional starch does not add significant benefits because the crystals have been combined such that there are no other gypsum crystal sites to which the starch adheres or binds. Therefore, since the bonding between the gypsum crystals and the molecules of the pregelatinized and partially hydrolyzed starch prepared according to the embodiment of the present invention is optimal, the strength of the crystalline gypsum matrix is enhanced, and the starch required for the strength is known and conventionally known. Less starch. The inventors have discovered that, in some embodiments, a dissolved starch molecule having a medium range viscosity, such as a medium range molecular weight starch, allows the starch molecule mobility to align the starch molecules with the gypsum crystals to optimize Good hydrogen bond formation between starch and gypsum and core strength.

In some embodiments, prepared according to some embodiments of the invention The pregelatinized and partially hydrolyzed starch also provides an advantage in terms of water demand. The addition of conventional pregelatinized starch to the gypsum slurry requires the addition of additional water to the gypsum slurry to maintain the desired degree of slurry fluidity. This is because conventional pregelatinized starch increases the viscosity of the gypsum slurry and reduces its fluidity. Thus, the use of pregelatinized starch in conventional systems has increased the demand for water such that even an excess of water will be required in the gypsum slurry.

Unexpectedly and unexpectedly, pregelatinized and partially hydrolyzed starch prepared according to embodiments of the present invention (especially starch having a desired medium range viscosity) requires less water to allow for water requirements in the gypsum slurry The effect is reduced, especially compared to conventional starch reduction. Moreover, because of the efficiency of pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention, less starch can be used, and according to some embodiments of the present invention, the positive impact on water demand may be even more pronounced. This lower water demand provides considerable efficiency during manufacturing. For example, excess water requires energy input for drying. Line speed must be slowed to accommodate drying. Thus, by reducing the water loading in the gypsum slurry, fewer energy sources and costs as well as faster production rates are seen. In some embodiments, the increase in water demand in the gypsum slurry is less than the increase in water demand required for other starches, such as, for example, a prepreg prepared by a different method having a viscosity greater than 700 centipoise (eg, about 773 centipoise). Gelatinized starch.

Any suitable non-pregelatinized starch may be selected in the preparation of the pregelatinized and partially hydrolyzed starch as long as it is sufficiently pregelatinized and acid modified in the extruder. As used herein, "starch" refers to a composition comprising a starch component. Thus, the starch may be 100% pure starch or may have other components, such as those commonly found in flour, such as proteins and fibers, as long as the starch group The fractions may constitute at least about 75% by weight of the starch composition. The starch may be in the form of a flour containing starch (e.g., corn flour), such as flour having at least about 75% (e.g., at least about 80%, at least about 85%, at least about 90%, at least about 95%, etc.) starch by weight of the flour. . By way of example and without limitation, the starch may be in the form of corn flour containing starch.

In some embodiments, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can be prepared to have the desired cold water solubility. Conventional pregelation techniques involve making the starch cold water soluble and generally requiring cooking the starch in excess water. However, such prior art techniques are not effective. Extrusion in accordance with embodiments of the present invention allows for a combination of heating and mechanical shearing that is unexpectedly and unexpectedly useful for pregelatinization and partial production with lower moisture content and cold water solubility in a single-step process. Energy-saving method for hydrolyzing starch. Cold water solubility is defined as any amount that can be dissolved in water at room temperature (about 25 ° C). Starches that exhibit solubility in cold water have been found to provide significant benefits for the strength of gypsum products such as siding. The cold water soluble starch of the present invention has a cold water solubility of greater than about 30% and can increase the strength of the gypsum core material when added to the set gypsum core material. The solubility of pregelatinized starch in water is defined as the amount of starch dissolved in room temperature water divided by the total amount of starch.

In some embodiments, the pregelatinized and partially hydrolyzed starch prepared according to embodiments of the present invention has a cold water solubility of from about 30% to about 100%. In other embodiments, the extruded pregelatinized and partially hydrolyzed starch has a cold water solubility of from about 50% to about 100%. In an embodiment of the invention, the cold pre-gelatinized and partially hydrolyzed starch may be as cold water soluble as listed in Table 2, for example. In the table, "X" indicates the range "about [corresponding value in the top column] to about [corresponding to the leftmost column) value]". The indicated values indicate the cold water solubility of the pregelatinized and partially hydrolyzed starch prepared according to the examples of the present invention extruded (Table 2). For ease of presentation, each value indicates "about" the value. For example, the first "X" in Table 2 is the range "about 30% to about 35%". The range of the table is between the start and end points and includes the start and end points.

While not wishing to be bound by any particular theory, the combination of mechanical energy and thermal energy during extrusion is responsible for the cold water solubility of the pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention. When the starch undergoes extrusion, the hydrogen bonds between the starch molecules break. When the extruded starch is dissolved in water, the starch hydrogen bonds with water molecules. After the pregelatinization process, the extruded pregelatinized and partially hydrolyzed starch molecules freely form hydrogen bonds with the gypsum crystals, thus imparting higher strength to the gypsum product. Therefore, the starch required is less compared to conventional starch because of the strength of the modified gypsum siding exhibiting solubility in cold water.

In some embodiments, the pregelatinized and partially hydrolyzed starch has a cold water viscosity (10% solids, 25 ° C) of from about 10 BU to about 120 BU, such as about 20 BU, as measured according to the Brabender method described herein. About 110 BU, about 30 BU to about 100 BU, about 40 BU to about 90 BU, about 50 BU to about 80 BU, or about 60 BU to about 70 BU.

Preparation of starch for use according to the method in the production of the board

In some embodiments, the pre-gelatinized and partially hydrolyzed starch can be formed into a board (eg, gypsum wallboard) by mixing at least water, non-pregelatinized starch, and acid to form a moisture content of about From 8% by weight to about 25% by weight of a wet starch precursor selected from the group consisting of a weak acid selected from substantially avoiding chelation of calcium ions, a strong acid in an amount of about 0.01% by weight or less, or any weight thereof, based on the weight of the starch, or any combination.

The wet starch precursor is then fed into an extruder wherein the temperature of the mold is from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F), The moist starch is pregelatinized and acid modified to at least partially hydrolyze. The pregelatinized and partially hydrolyzed starch can then be mixed with at least water and stucco to form a slurry which can then be placed between the first cover sheet and the second cover sheet to form a wetted assembly. The wetted assembly can then be cut into sheets which are then dried. Preferably, the set gypsum core material has a compressive strength greater than that of a set gypsum core material prepared using starch prepared in a different manner.

Pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can unexpectedly and unexpectedly be included in the slurry in relatively low amounts (as solids/solids) and still achieve significant strength enhancement in the sheet. . Thus, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention may be included in the gypsum slurry in an amount of from about 0.1% to about 10% by weight, based on the weight of the stucco, for example from about 0.5% to about 10%. .

In some embodiments, it has been found that increasing the amount of pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention in the slurry beyond these ranges does not effectively improve strength because after adding even more starch The intensity level can enter the flat line area to some extent. However, higher starch levels can be utilized if desired, especially where the strength gains are diminished.

In an embodiment of the invention, the pregelatinized and partially hydrolyzed starch may be added to the gypsum slurry as, for example, the amounts listed in Tables 3A and 3B below. In the table, "X" indicates the range "about [corresponding value in the top column] to about [corresponding value in the leftmost column]". The value indicated indicates the amount of starch in the form of a percentage by weight of stucco. For ease of presentation, each value indicates "about" the value. For example, the first "X" is in the range "about 0.1% starch by weight of stucco to about 0.25% starch by weight of stucco".

Thus, the amount of pregelatinized and partially hydrolyzed starch prepared in accordance with an embodiment of the present invention added to the slurry can range between any of the aforementioned endpoints set forth in Table 3A or 3B and includes Any of them.

In some embodiments of various applications, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention may be added to the slurry in combination with other starches. For example, in the case of gypsum wallboard as described below, the partially gelled partial hydrolysis prepared according to embodiments of the present invention can be combined with other starches to enhance core strength and paper-core bond, especially if Accept to increase some water demand.

Thus, in some embodiments of the invention, the gypsum slurry may comprise one or more pregelatinized and partially hydrolyzed starches prepared according to embodiments of the invention and one or more other types of starch. Other starches may include, for example, pregelatinized starch having a viscosity below 20 centipoise and/or above 700 centipoise. One example is pregelatinized corn starch (e.g., corn starch having a viscosity of more than 700 centipoise, such as about 773 centipoise). Other starches may also be, for example, non-pregelatinized starch (such as acid modified starch) and ungelatinized alkylated starch (such as ethylated starch) and the like. The combination of starch may be pre-mixed prior to addition to the gypsum slurry (eg, may be pre-mixed with the other components, such as stucco, in the anhydrous mixture, or pre-mixed with the other wetting ingredients in the wet mixture), or It can be included in the gypsum slurry one at a time, or any variation thereof. Pre-gelatinized partially hydrolyzed and other starches prepared in accordance with embodiments of the present invention may be included in any suitable ratio.

For example, the pregelatinized and partially hydrolyzed starch prepared according to embodiments of the present invention added to the gypsum slurry as a percentage of total starch content may have a starch content of, for example, at least about 10% by weight, such as at least about 20%. At least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 99%, at least about 100% Or any range between the two. In some embodiments, the ratio of pregelatinized and partially hydrolyzed starch prepared according to embodiments of the invention to other starches can be about 25:75, about 30:70, about 35:65, about 50:50, about 65:35, about 70:30, about 75:25, etc.

In some embodiments, in addition to the starch component, the slurry is formulated to include water, stucco, a blowing agent (sometimes referred to simply as "foam"), and other additives as needed. Unexpectedly and unexpectedly, in accordance with some embodiments, particularly in accordance with such embodiments exhibiting a range of viscosity, it has been found desirable to add to maintain slurry fluidity with and without pregelatinization and partially hydrolyzed starch (based on The amount of water at the same level of slurry fluidity in the case of the embodiment of the present invention prepared in an extruder is less than the amount of water required to use pregelatinized and partially hydrolyzed starch prepared according to different methods. The plaster can be calcium sulfate alpha hemihydrate, In the form of calcium sulfate beta hemihydrate and/or calcium sulfate anhydrite. Stucco can be fibrous or non-fibrous. A blowing agent may be included to form an air void distribution within the continuous crystalline matrix of set gypsum. In some embodiments, the blowing agent comprises a stabilizing component of a major weight portion and a stabilizing component of a minor weight portion (eg, wherein the combination is unstable and stable/unstable blends). The weight ratio of the unstable component to the stabilizing component effectively forms an air void distribution within the set gypsum core. See, for example, U.S. Patent Nos. 5,643,510; 6,342,284; and 6,632,550.

Suitable void distributions and wall thicknesses (independently) have been found to be effective in enhancing strength, especially in lower density (e.g., below about 35 pcf) panels. See, for example, US 2007/0048490 and US 2008/0090068. Evaporated water voids having a void diameter generally of about 5 [mu]m or less also contribute to the overall void distribution as well as the aforementioned air (foam) voids. In some embodiments, the volume ratio of voids having a pore size greater than about 5 microns to voids having a pore size of about 5 microns or less is from about 0.5:1 to about 9:1, such as from about 0.7:1 to about 9: 1. From about 0.8:1 to about 9:1, from about 1.4:1 to about 9:1, from about 1.8:1 to about 9:1, from about 2.3:1 to about 9:1, from about 0.7:1 to about 6: 1. From about 1.4:1 to about 6:1, from about 1.8:1 to about 6:1, from about 0.7:1 to about 4:1, from about 1.4:1 to about 4:1, from about 1.8:1 to about 4: 1. From about 0.5:1 to about 2.3:1, from about 0.7:1 to about 2.3:1, from about 0.8:1 to about 2.3:1, from about 1.4:1 to about 2.3:1, from about 1.8:1 to about 2.3: 1 and so on. In some embodiments, the blowing agent is present in the slurry in an amount of, for example, less than about 0.5% by weight of the stucco, such as from about 0.01% to about 0.5%, from about 0.01% to about 0.4%, by total weight of the stucco. From about 0.01% to about 0.3%, from about 0.01% to about 0.2%, from about 0.01% to about 0.1%, from about 0.02% to about 0.4%, from about 0.02% to about 0.3%, from about 0.02% to about 0.2%, and the like.

In some embodiments, additives such as accelerators (e.g., wet gypsum accelerators, heat resistant accelerators, climatic stabilizing accelerators) and retarders are well known and can be included. See, for example, U.S. Patents 3,573,947 and 6,409,825. In some embodiments in which the accelerator and/or retarder are included, the amount of solids of each of the accelerator and/or retarder in the gypsum slurry can be, for example, from about 0% to about 10% by weight of the stucco (eg, about From 0.1% to about 10%), such as from about 0% to about 5% by weight of the stucco (e.g., from about 0.1% to about 5%). Other additives may be included as needed to impart strength, for example, to enable lower weight products to have sufficient strength, to avoid permanent deformation, to increase green strength (eg, as the product travels along the manufacturing line and solidify on the conveyor), to enhance fire resistance, Improve water resistance and so on.

For example, in some embodiments, the slurry may optionally include at least one dispersant to enhance flow. As with the pregelatinized and partially hydrolyzed starch and other ingredients prepared in accordance with embodiments of the present invention, the dispersing agent may be included with the other anhydrous ingredients in anhydrous form and/or together with other liquid ingredients in liquid form including the core stock slurry. in. Examples of the dispersant include naphthalenesulfonates such as polynaphthalenesulfonic acid and salts thereof (polynaphthalenesulfonate) and derivatives which are condensation products of naphthalenesulfonic acid and formaldehyde; and polycarboxylate dispersants such as poly Carboxylic acid ethers, such as PCE211, PCE111, 1641, 1641F or PCE 2641 type dispersants, such as MELFLUX 2641F, MELFLUX 2651F, MELFLUX 1641F, MELFLUX 2500L dispersant (BASF) and COATEX Ethacryl M available from Coatex, Inc.; And / or lignosulfonate or sulfonated lignin. The lignosulfonate is a water soluble anionic polyelectrolyte polymer which is a by-product of the use of sulphite pulping to produce wood pulp. An example of a lignin suitable for use in practicing the principles of the embodiments of the present invention is available from Reed Lignin Inc. Marasperse C-21.

Low molecular weight dispersants are generally preferred. Low molecular weight naphthalene sulfonate dispersants are advantageous because their water demand tends to be lower than higher viscosity, higher molecular weight dispersants. Thus, a molecular weight of from about 3,000 to about 10,000 (e.g., from about 8,000 to about 10,000) is preferred. As another illustration, for a PCE211 type dispersant, in some embodiments, the molecular weight can range from about 20,000 to about 60,000, which exhibits less retardation than a dispersant having a molecular weight greater than 60,000.

An example of a naphthalenesulfonate is DILOFLO available from GEO Specialty Chemicals. DILOFLO is a 45% aqueous solution of naphthalene sulfonate, although other aqueous solutions (e.g., having a solids content ranging from 35% to about 55% by weight) are readily available. The naphthalene sulfonate can be used in the form of an anhydrous solid or powder, such as LOMAR D available from GEO Specialty Chemicals. Another exemplary naphthalenesulfonate is DAXAD available from Hampshire Chemical Corp.

If included, the dispersing agent can be included in any suitable (solid/solid) amount, such as from about 0.1% to about 5% by weight of the stucco, such as from about 0.1% to about 4%, from about 0.1% to about 3%. From about 0.2% to about 3%, from about 0.5% to about 3%, from about 0.5% to about 2.5%, from about 0.5% to about 2%, from about 0.5% to about 1.5%, and the like.

In some embodiments, if desired, one or more phosphoric acid containing compounds may also be included in the slurry, as appropriate. For example, the phosphoric acid-containing components suitable for use in some embodiments include water soluble components and may be in the form of ions, salts or acids, ie condensed phosphoric acids, each of which comprises two or more phosphoric acids. Unit; a salt or ion of a condensed phosphate, each of which contains two Or two or more phosphoric acid units; and a monobasic or monovalent ion of orthophosphate and a water-soluble acyclic polyphosphate. See, for example, U.S. Patent Nos. 6,342,284; 6,632,550; 6,815,049; and 6,822,033.

In some embodiments, if a phosphoric acid composition is added, biostrength, resistance to permanent deformation (eg, sagging), dimensional stability, and the like can be enhanced. Tri-metaphosphate compounds can be used, including, for example, sodium trimetaphosphate, potassium trimetaphosphate, lithium trimetaphosphate, and ammonium trimetaphosphate. Sodium trimetaphosphate (the STMP) preferred, although other suitable phosphates may be, for example, comprise four sodium metaphosphate, having from about 6 to about 27 repeating phosphate units and having the molecular formula _{Na n + 2 P n O 3n} + 1 ( where n =6-27) sodium hexametaphosphate, tetrapotassium pyrophosphate having the molecular formula K ₄ P ₂ O ₇ , trisodium dipotassium triphosphate having the molecular formula Na ₃ K ₂ P ₃ O ₁₀ , having the molecular formula Na ₅ P ₃ O ₁₀ sodium tripolyphosphate, tetrasodium pyrophosphate of molecular formula Na ₄ P ₂ O ₇ , aluminum trimetaphosphate having molecular formula Al(PO ₃ ) ₃ , sodium pyrophosphate having molecular formula Na ₂ H ₂ P ₂ O ₇ , Ammonium polyphosphate having 1,000 to 3,000 repeating phosphate units and having the formula (NH ₄ ) _n+2 P _n O _3n+1 (where n=1,000-3,000) or having two or more repeating phosphate units and having a molecular formula H _n+2 P _n O _3n+1 (where n is two or more) polyphosphoric acid.

In some embodiments, the phosphoric acid can be included in anhydrous form or in the form of an aqueous solution (eg, from about 5% to about 20% phosphoric acid solution, such as about 10% solution). If included, the phosphoric acid can be any suitable amount (based on solids/solids), such as from about 0.01% to about 0.5% by weight, based on the weight of the stucco, such as from about 0.03% to about 0.4% by weight of the stucco. From about 0.1% to about 0.3% by weight or from about 0.12% to about 0.4% by weight.

Suitable for fire and/or waterproof products, depending on the situation Additives, including, for example, decane (water repellency); fibers; heat sink additives such as aluminum trihydrate (ATH), magnesium hydroxide or the like; and/or high expansion particles (eg, when heated at 1560 °F) It can be expanded to about 300% or more of the original volume in one hour). For a description of these and other components, see, for example, co-pending U.S. Application Serial No. 13/400,010 (filed on February 17, 2012). In some embodiments, high expansion vermiculite is included, although other refractory materials may be included. Some of the fire related product panels of the present invention may have a Thermal Insulation Index (TI) of about 17 minutes or more, such as about 20 minutes or more, about 30 minutes or more, about 45 minutes or more, about 60 minutes or Higher; and/or high temperature shrinkage (at a temperature of about 1560 °F (850 °C)) less than about 10% in the xy direction and greater than about 20% expansion in the z direction. The fire resistance or water repellency additive may be included in any suitable amount as needed, depending on, for example, the fire rating. For example, if included, the amount of fire resistant or water repellent additive can range from about 0.5% to about 10% by weight of the stucco, such as from about 1% to about 10% by weight of the stucco, from about 1% to about 8%, from about 2% to about 10%, from about 2% to about 8%, and the like.

If included, in some embodiments, the decane is preferably added in the form of an emulsion. The slurry is then shaped and dried under conditions which promote the polymerization of the oxane to form a highly crosslinked polyoxyxene resin. A catalyst that promotes the polymerization of decane can be added to the gypsum slurry to form a highly crosslinked polyoxyl resin. In some embodiments, a solventless methylhydrooxane fluid sold by Wacker-Chemie GmbH (Munich, Germany) under the name SILRES BS 94 can be used as the decane. This product is a non-aqueous solvent or a solvent. It is contemplated that in some embodiments, from about 0.3% to about 1.0% of BS 94 oxirane may be employed by weight of the anhydrous component. For example, in some embodiments, the weight of the anhydrous plaster Preferably, from about 0.4% to about 0.8% of a decane is used.

The slurry formulation can be made at any suitable water/stucco ratio, for example from about 0.4 to about 1.3. However, because pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention is required to be added to the slurry containing it as compared to other starches, such as conventional pregelatinized starch prepared according to various methods. The amount of water is reduced, so the water/stucco ratio input used to formulate the slurry can be lower than the conventionally known ratio of gypsum slurry containing other starches (especially at lower weights/densities). For example, in some embodiments, the water/stucco ratio can be from about 0.4 to about 1.1, from about 0.4 to about 0.9, from about 0.4 to about 0.85, from about 0.45 to about 0.85, from about 0.55 to about 0.85, from about 0.55 to From about 0.8, from about 0.6 to about 0.9, from about 0.6 to about 0.85, from about 0.6 to about 0.8, and the like.

The cover sheet can be formed from any suitable material and basis weight. Advantageously, the core material formed from the slurry comprising the pregelatinized and partially hydrolyzed starch prepared according to an embodiment of the present invention provides sufficient strength even in a panel having a substantially lower weight cover sheet, such as In some embodiments, even for lower weight plates (e.g., having a density of about 35 pcf or less), less than 45 lbs/MSF (e.g., about 33 lbs/MSF to 45 lbs/MSF). However, if desired, in some embodiments, heavier basis weights may be used to, for example, further enhance pinning resistance or enhance handling, such as to facilitate the desired "tactile" characteristics of the end user.

In some embodiments, one or both of the cover sheets may be formed from paper and have a basis weight of, for example, at least about 45 lbs/MSF (eg, about 45 lbs/MSF), especially for lower density boards (eg, staple strength). Up to about 65 lbs/MSF, about 45 lbs/MSF to about 60 lbs/MSF, about 45 lbs/MSF to About 55 lbs/MSF, about 50 lbs/MSF to about 65 lbs/MSF, about 50 lbs/MSF to about 60 lbs/MSF, etc.). If desired, in some embodiments, a cover sheet (e.g., a "surface" paper side when installed) may have the aforementioned higher basis weight to enhance, for example, tack resistance and handling while another cover sheet ( For example, a "back" sheet when the panel is placed) may have a lower weight to some extent if desired (eg, a weight basis of less than about 45 lbs/MSF, such as from about 33 lbs/MSF to about 45 lbs/MSF or about 33 lbs/ MSF to about 40 lbs/MSF).

The board weight is a function of thickness. Since the panels are typically made in varying thicknesses, the panel density is used herein as a measure of the weight of the panel. The advantages of pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can be seen across various plate densities, such as below about 40 pcf or 40 pcf, such as from about 20 pcf to about 40 pcf, from about 24 pcf to about 37 pcf, and the like. However, preferred embodiments of the present invention have particular utility at lower densities, wherein the strength enhancement provided by the pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention advantageously enables the use of lower weight panels capable of strength It is good and requires less water than plates made from other starches prepared according to different methods.

For example, in some embodiments, the plate density can range from about 20 pcf to about 35 pcf, such as from about 20 pcf to about 34 pcf, from about 20 pcf to about 33 pcf, from about 20 pcf to about 32 pcf, from about 20 pcf to about 31 pcf, from about 20 pcf to about 30 pcf. From about 20 pcf to about 29 pcf, from about 21 pcf to about 35 pcf, from about 21 pcf to about 34 pcf, from about 21 pcf to about 33 pcf, from about 21 pcf to about 32 pcf, from about 21 pcf to about 31 pcf, from about 21 pcf to about 30 pcf, from about 21 pcf to about 29 pcf, about 24 pcf to about 35 pcf, about 24 pcf to about 34 pcf, about 24 pcf to about 33 pcf, about 24 pcf to about 32 pcf, about 24 pcf to about 31 pcf, about 24pcf to about 30pcf or about 24pcf to about 29pcf.

Pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention may be added to the slurry to provide strength enhancement of the products of the present invention, which may be particularly beneficial at lower weights/densities. For example, in some embodiments, a panel made in accordance with an embodiment of the present invention has a compressive strength at a density of 29 pcf of at least about 400 psi (2,750 kPa) as tested according to the method set forth in Example 4. . Advantageously, in various embodiments of various panel densities as described herein, the panels produced by the method of the present invention can be prepared to have a compressive strength of at least about 400 psi, such as at least about 450 psi (3,100 kPa), at least about 500 psi (3,450). kPa), at least about 550 psi (3,800 kPa), at least about 600 psi (4,100 kPa), at least about 650 psi (4,500 kPa), at least about 700 psi (4,800 kPa), at least about 750 psi (5,200 kPa), at least about 800 psi (5,500 kPa). At least about 850 psi (5,850 kPa), at least about 900 psi (6,200 kPa), at least about 950 psi (6,550 kPa), or at least about 1,000 psi (6,900 kPa). Additionally, in some embodiments, the compressive strength can be bound by any two of the foregoing. For example, the compressive strength can be between about 450 psi and about 1,000 psi (eg, between about 500 psi and about 900 psi, between about 600 psi and about 800 psi, etc.).

In some embodiments, the panels made in accordance with the present invention conform to the testing protocol according to ASTM Standard C473-10. For example, in some embodiments, when the panel is cast at a thickness of 1⁄2, the panel has a tack resistance of at least about 65 lb, such as at least about 68 lb, at least about 70 lb, as determined according to ASTM C473-10. At least about 72 lb, at least about 75 lb, at least about 77 lb, and the like. In various embodiments, the tack resistance can be from about 68 lb to about 100 lb, such as about 68 lb to From about 95 lb, from about 68 lb to about 90 lb, from about 68 lb to about 85 lb, from about 68 lb to about 80 lb, from about 68 lb to about 77 lb, from about 68 lb to about 75 lb, from about 68 lb to about 72 lb, from about 68 lb to about 70 lb, from about 70 lb to about 100 lb. From about 70 lb to about 95 lb, from about 70 lb to about 90 lb, from about 70 lb to about 85 lb, from about 70 lb to about 80 lb, from about 70 lb to about 77 lb, from about 70 lb to about 75 lb, from about 70 lb to about 72 lb, from about 72 lb to about 100 lb, about 72 lb to about 95 lb, about 72 lb to about 90 lb, about 72 lb to about 85 lb, about 72 lb to about 80 lb, about 72 lb to about 77 lb, about 72 lb to about 75 lb, about 75 lb to about 100 lb, about 75 lb to about 95 lb, about 75 lb to From about 90 lb, from about 75 lb to about 85 lb, from about 75 lb to about 80 lb, from about 75 lb to about 77 lb, from about 77 lb to about 100 lb, from about 77 lb to about 95 lb, from about 77 lb to about 90 lb, from about 77 lb to about 85 lb, or from about 77 lb to about 80 lb. .

With respect to flexural strength, in some embodiments, the flexural strength of the panel is at least about 36 lb in the machine direction when the cast sheet is cast, as determined according to ASTM Standard C473, for example, at least about 38 lb, at least About 40 lb, etc.) and/or at least about 107 lb (eg, at least about 110 lb, at least about 112 lb, etc.) in a direction that intersects the machine direction. In various embodiments, the flexural strength of the sheet in the machine direction can range from about 36 lbs to about 60 lbs, such as from about 36 lbs to about 55 lbs, from about 36 lbs to about 50 lbs, from about 36 lbs to about 45 lbs, from about 36 lbs to about 40 lbs, from about 36 lbs. Up to about 38 lb, about 38 lb to about 60 lb, about 38 lb to about 55 lb, about 38 lb to about 50 lb, about 38 lb to about 45 lb, about 38 lb to about 40 lb, about 40 lb to about 60 lb, about 40 lb to about 55 lb, about 40 lb to about 50 lb or from about 40 lb to about 45 lb. In various embodiments, the flexural strength of the panel in a direction that intersects the machine direction can be from about 107 lb to about 130 lb, such as From about 107 lb to about 125 lb, from about 107 lb to about 120 lb, from about 107 lb to about 115 lb, from about 107 lb to about 112 lb, from about 107 lb to about 110 lb, from about 110 lb to about 130 lb, from about 110 lb to about 125 lb, from about 110 lb to about 120 lb, about From 110 lb to about 115 lb, from about 110 lb to about 112 lb, from about 112 lb to about 130 lb, from about 112 lb to about 125 lb, from about 112 lb to about 120 lb, or from about 112 lb to about 115 lb.

Additionally, in some embodiments, the average core hardness of the panels can be at least about 11 lb, such as at least about 12 lb, at least about 13 lb, at least about 14 lb, at least about 15 lb, at least about 16 lb, as determined according to ASTM C473-10. At least about 17 lb, at least about 18 lb, at least about 19 lb, at least about 20 lb, at least about 21 lb, or at least about 22 lb. In some embodiments, the core hardness of the board can be from about 11 lb to about 25 lb, such as from about 11 lb to about 22 lb, from about 11 lb to about 21 lb, from about 11 lb to about 20 lb, from about 11 lb to about 19 lb, from about 11 lb to about 18 lb, From about 11 lb to about 17 lb, from about 11 lb to about 16 lb, from about 11 lb to about 15 lb, from about 11 lb to about 14 lb, from about 11 lb to about 13 lb, from about 11 lb to about 12 lb, from about 12 lb to about 25 lb, from about 12 lb to about 22 lb, from about 12 lb. Up to about 21 lb, about 12 lb to about 20 lb, about 12 lb to about 19 lb, about 12 lb to about 18 lb, about 12 lb to about 17 lb, about 12 lb to about 16 lb, about 12 lb to about 15 lb, about 12 lb to about 14 lb, about 12 lb to about 13 lb, from about 13 lb to about 25 lb, from about 13 lb to about 22 lb, from about 13 lb to about 21 lb, from about 13 lb to about 20 lb, from about 13 lb to about 19 lb, from about 13 lb to about 18 lb, from about 13 lb to about 17 lb, from about 13 lb to about 16 lb, From about 13 lb to about 15 lb, from about 13 lb to about 14 lb, from about 14 lb to about 25 lb, from about 14 lb to about 22 lb, from about 14 lb to about 21 lb, from about 14 lb to about 20 lb, from about 14 lb to about 19 lb, from about 14 lb to From about 18 lb, from about 14 lb to about 17 lb, from about 14 lb to about 16 lb, from about 14 lb to about 15 lb, from about 15 lb to about 25 lb, from about 15 lb to about 22 lb, from about 15 lb to about 21 lb, from about 15 lb to about 20 lb, from about 15 lb to about 19 lb. From about 15 lb to about 18 lb, from about 15 lb to about 17 lb, from about 15 lb to about 16 lb, from about 16 lb to about 25 lb, from about 16 lb to about 22 lb, from about 16 lb to about 21 lb, from about 16 lb to about 20 lb, from about 16 lb to about 19 lb, about From 16 lb to about 18 lb, from about 16 lb to about 17 lb, from about 17 lb to about 25 lb, from about 17 lb to about 22 lb, from about 17 lb to about 21 lb, from about 17 lb to about 20 lb, from about 17 lb to about 19 lb, from about 17 lb to about 18 lb, from about 18 lb to From about 25 lb, from about 18 lb to about 22 lb, from about 18 lb to about 21 lb, from about 18 lb to about 20 lb, from about 18 lb to about 19 lb, from about 19 lb to about 25 lb, from about 19 lb to about 22 lb, from about 19 lb to about 21 lb, from about 19 lb to about 20 lb. From about 21 lb to about 25 lb, from about 21 lb to about 22 lb, or from about 22 lb to about 25 lb.

At least in part due to the generation of the mid-range viscosity characteristics of some embodiments of the invention, even for ultra-light density boards as described herein (eg, about 31 pcf or less) may meet such criteria (eg, staple resistance) , flexural strength and core hardness).

The present inventors have also discovered that the temperature-increasing solidification (TRS) hydration rate exhibited by pregelatinized and partially hydrolyzed starch prepared according to an embodiment of the present invention is comparable to conventional pregelatinized starch prepared according to various methods. The rate is equal or exceeded. The desired setting time can vary depending on the formulation, and the desired setting time can be determined by those skilled in the art, depending on the plant conditions and the materials available.

Products according to embodiments of the invention may be on a typical manufacturing line be made of. For example, the board manufacturing technique is described in, for example, U.S. Patent No. 7,364,676 and U.S. Patent Application Publication No. 2010/0247937. In short, in the case of a gypsum board, the method generally involves discharging the cover sheet onto a mobile conveyor. In these embodiments, the cover sheet is a "surface" cover sheet because the gypsum board is typically "surface down".

The anhydrous and/or wet components of the gypsum slurry are fed into a mixer (e.g., a pin mixer) where it is agitated to form a gypsum slurry. The mixer comprises a body and a discharge tube (e.g., a gate-can-feed tube configuration as known in the art or a configuration as described in U.S. Patent Nos. 6,494,609 and 6,874,930). For example, in some embodiments, the vent tube can include a slurry dispenser having a single feed inlet or a plurality of feed inlets, such as US Patent Application Publication No. 2012/0168527 A1 (Application No. 13/341,016) And the discharge pipes described in the U.S. Patent Application Publication No. 2012/0170403 A1 (Application No. 13/341,209). In their embodiments, a slurry distributor having a plurality of feed inlets is used, which may include suitable splitters, such as those described in U.S. Patent Application Publication No. 2012/0170403 A1. If desired, a blowing agent can be added to the discharge tube of the mixer (e.g., in the gates as described in, for example, U.S. Patent Nos. 5,683,635 and 6,494,609) or in the body. The slurry discharged from the discharge pipe after all the components (including the blowing agent) have been added is the original gypsum slurry and the core material will be formed. This core material slurry is discharged onto the moving surface cover sheet.

The surface covering sheet may have a thin slag coating in the form of a relatively dense slurry layer. Additionally, the hard edges known in the art can be formed, for example, from the same slurry stream that forms the surface slag coating. In which the foam is inserted to the discharge In an embodiment of the tube, the secondary gypsum slurry stream can be removed from the mixer body to form a dense slag coating slurry that can then be used to form surface slag coatings and hard edges known in the art. . If included, the surface slag coating and hard edges are typically deposited on the moving surface cover sheet prior to deposition of the core slurry (typically upstream of the mixer). After discharge from the discharge tube, the core stock slurry is spread over the surface cover sheet (optionally with a slag coating) as needed and covered by a second cover sheet (usually a "back" cover sheet) to form a sandwich A wetted assembly of structural form which is the final board precursor. The second cover sheet may optionally be provided with a second slag coating which, if present, may be formed from a secondary (dense) gypsum slurry which is the same as or different from that used for the surface slag coating. The cover sheet may be formed from paper, fiber mat or other types of materials such as foils, plastics, glass mats, non-woven materials such as blends of cellulose and inorganic fillers, and the like.

The wetted assembly provided thereby is transported into a forming apparatus wherein the product is sized to a desired thickness (eg, via forming a sheet) and transported to one or more hob sections where the product is cut to the desired length . The wetted assembly is hardened to form an interlocking crystalline matrix of set gypsum, and excess water is removed using a drying process (e.g., by transporting the assembly through the kiln). Unexpectedly and unexpectedly, it has been found that panels prepared according to the present invention with pregelatinized and partially hydrolyzed starch prepared according to embodiments of the present invention require significantly less time in the drying process because of the water requirements of the starch. The quantity characteristics are low. This is advantageous because it reduces energy costs.

Vibration is also often used in the manufacture of gypsum boards to eliminate large voids or air pockets from the deposited slurry. Each of the above steps and for carrying out The processes and equipment of such steps are known in the art.

Pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can be used to formulate various products such as gypsum siding, acoustical (e.g., ceiling) bricks, joint compounds, gypsum-cellulosic fiber products (such as gypsum-wood fiber walls) Board) and its analogues. In some embodiments, such products may be formed from a slurry in accordance with embodiments of the present invention.

Thus, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention in an extruder can have the beneficial effects as described herein in products other than paper gypsum board. For example, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention can be used in a face top product (e.g., woven) wherein the sheet cover sheet is in the form of a fiber mat. These pads may optionally have a finish to reduce water permeability. Other ingredients that may be included in the manufacture of such underlying products, as well as materials and methods of manufacture for the fiber mats, are discussed in, for example, U.S. Patent No. 8,070,895, and U.S. Patent Application Publication No. 2009/0247937.

In addition, the gypsum-cellulosic product may, as desired, be a cellulose body particle (e.g., wood fiber), gypsum, pregelatinized and partially hydrolyzed starch and other ingredients prepared according to embodiments of the present invention (e.g., a water repellent additive such as helium oxygen). Alkane) form. Other ingredients and methods of manufacture are discussed, for example, in U.S. Patent Nos. 4,328,178, 4,239,716, 4,392,896, 4,645,548, 5,320,677, 5,817,262, and 7,413,603.

Illustrative example of an embodiment

In one embodiment, a method of making a pregelatinized and partially hydrolyzed starch comprises: (a) mixing at least water, non-pregelatinized starch, and substantial Avoiding chelation of the weak acid of calcium ions to produce a wet starch precursor having a moisture content of from about 8 wt% to about 25 wt%; (b) feeding the wet starch precursor to the extruder; and (c) The wet starch is pregelatinized and acid modified in an extruder at a mold temperature of from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F).

In another embodiment, the pressure inside the extruder is at least about 2,000 psi.

In another embodiment, the pregelatinized and partially hydrolyzed starch has a cold water solubility of greater than about 50%.

In another embodiment, the pregelatinized and partially hydrolyzed starch has a cold water viscosity (10% solids, 25 ° C) of from about 10 Brabender units (BU) to about 120 BU.

In another embodiment, the starch has a viscosity characteristic of from about 20 centipoise to about 700 centipoise when the pregelatinized and partially hydrolyzed starch undergoes a viscosity when subjected to conditions according to the VMA process.

In another embodiment, the pregelatinized and partially hydrolyzed starch has a viscosity (10% solids, 93 ° C) of from about 5 BU to about 33 BU.

In another embodiment, the weak acid that substantially avoids chelation of calcium ions comprises strontium.

In another embodiment, tartaric acid is included in the mixing to form a moist starch precursor.

In another embodiment, the amount of weak acid that substantially avoids chelation of calcium ions is from about 0.5% to about 5% by weight, based on the weight of the starch.

In another embodiment, the moisture content of the moist starch is The powder precursor weight ranges from about 10% by weight to about 20% by weight.

In another embodiment, the pregelatinization and acid upgrading are carried out in an extruder at a mold temperature of at least about 175 ° C (about 350 ° F) to about 205 ° C (about 400 ° F).

In another embodiment, the pregelatinized and partially hydrolyzed starch produces at least about 100 kg/hr in the extruder.

In another embodiment, the pregelatinization and acid upgrading are carried out in less than about 5 minutes.

In another embodiment, the pregelatinization and acid upgrading are carried out in less than about 1 minute.

In another embodiment, the method does not contain a purification step for pregelatinized and partially hydrolyzed starch.

In another embodiment, the method does not contain a neutralization step for pregelatinized and partially hydrolyzed starch.

In another embodiment, the pregelatinized and partially hydrolyzed starch is at least about 70% gelatinized.

In another embodiment, a pregelatinized and partially hydrolyzed starch is prepared in accordance with an embodiment of the present invention.

In another embodiment, a method of making a pregelatinized and partially hydrolyzed starch comprises: (a) mixing at least water, non-pregelatinized starch, and a strong acid to produce a moisture content of from about 8 wt% to about 25 wt%. a wet starch precursor, wherein the amount of the strong acid is about 0.05% by weight or less based on the weight of the starch; (b) feeding the wet starch precursor to the extruder; and (c) at the extrusion Machine at about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F) The moist starch is pregelatinized and acid modified at a mold temperature.

In another embodiment, a method of making a pregelatinized and partially hydrolyzed starch comprises: (a) mixing at least water, non-pregelatinized starch, and a strong acid to produce a moisture content of from about 8 wt% to about 25 wt%. a wet starch precursor, wherein the amount of the strong acid is about 0.01% by weight or less based on the weight of the starch; (b) feeding the wet starch precursor to the extruder; and (c) at the extrusion The wet starch is pregelatinized and acid modified at a mold temperature of from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F).

In another embodiment, the strong acid has a pKa of about -1.7 or -1.7 or less.

In another embodiment, the strong acid is sulfuric acid, nitric acid, hydrochloric acid, or any combination thereof.

In another embodiment, the method of making a board comprises: (a) forming a pregelatinized and partially hydrolyzed starch by: (i) mixing at least water, non-pregelatinized starch, and acid to form a moisture content of From about 8 wt% to about 25 wt% of the wet starch precursor selected from the group consisting of (1) a weak acid that substantially avoids chelation of calcium ions, and (2) an amount based on the weight of the starch a strong acid of about 0.05% by weight or less, or (3) any combination thereof; (ii) feeding the wet starch precursor into an extruder; and (iii) having a temperature of about 150 ° C (about 300) The wet starch is pregelatinized and acid modified in an extruder of a mold at a temperature of about 210 ° C (about 410 ° F); (b) mixing the pregelatinized and partially hydrolyzed starch with at least Water and mortar to form a slurry; (c) placing the slurry between the first cover sheet and the second cover sheet to form a wetted assembly; (d) cutting the wetted assembly into a sheet; and (e Dry the plate.

In another embodiment, the amount of strong acid is about 0.01% by weight or less based on the weight of the starch.

In another embodiment, a method of making a board comprises: (a) forming a pregelatinized and partially hydrolyzed starch by: (i) mixing at least water, non-pregelatinized starch, and substantially avoiding sequestration a weak acid of calcium ions to produce a wet starch precursor having a moisture content of from about 8 wt% to about 25 wt%; (ii) feeding the wet starch precursor to an extruder; and (iii) having a temperature of about 150 ° C The wet starch is pregelatinized and acid modified in an extruder of a mold (about 300 °F) to a temperature of about 210 ° C (about 410 ° F); (b) mixing the pregelatinized and partially hydrolyzed Starch and at least water and mortar to form a slurry; (c) placing the slurry between the first cover sheet and the second cover sheet to form a wet assembly; (d) cutting the wet assembly into a sheet; And (e) drying the plate.

In another embodiment, a method of making a board comprises: (a) mixing at least water, non-pregelatinized starch, and a strong acid to produce a wet starch precursor having a moisture content of from about 8 wt% to about 25 wt%, wherein The amount of the strong acid is about 0.05% by weight or less based on the weight of the starch; (ii) the wet starch precursor is fed into the extruder; and (iii) is at about 150 ° C (about 300 ° F) The pre-gelatinized and acid-modified starch in an extruder of a mold at a temperature of about 210 ° C (about 410 ° F); (b) mixing the pre-gelatinized and partially hydrolyzed starch with at least water And stucco to form a slurry; (c) placing the slurry between the first cover sheet and the second cover sheet to form a wetted assembly; (d) cutting the wetted assembly into a sheet; and (e) Dry the plate.

In another embodiment, the amount of strong acid is about 0.01% by weight or less based on the weight of the starch.

In another embodiment, the set gypsum core material has a compressive strength greater than that of a set gypsum core material made using starch prepared in a different manner.

In another embodiment, the pregelatinized and partially hydrolyzed starch is at least about 70% gelled when added to the slurry, and additional gelation occurs during the drying step.

In another embodiment, the pregelatinized and partially hydrolyzed starch is fully gelatinized when added to the slurry.

In another embodiment, the plate has a compressive strength of at least about 400 psi (2,800 kPa) at a density of 29 pcf.

In another embodiment, the core hardness of the sheet is at least about 11 as determined according to ASTM C473-10.

In another embodiment, the plate density is from about 21 pcf to about 35 pcf.

In another embodiment, the slurry further comprises sodium trimetaphosphate.

In another embodiment, the amount of water that needs to be added to maintain slurry fluidity at the same level as the slurry without pregelatinized and partially hydrolyzed starch is less than the use of pre-gels prepared according to different methods. The amount of water required to coagulate and partially hydrolyze the starch increases.

In another embodiment, the amount of starch is from about 0.5% to about 10% by weight, based on the weight of the stucco.

In another embodiment, a wall panel is prepared in accordance with an embodiment of the present invention.

It should be noted that the foregoing is merely an example of an embodiment. From this article All the illustrative embodiments are apparent from the full description. It will also be understood by one of ordinary skill in the art that each of these embodiments can be used in various combinations with other embodiments provided herein.

The following examples further illustrate the invention but are not to be construed as limiting its scope in any way.

Example 1

This example illustrates the preparation of pregelatinized and partially hydrolyzed starch in accordance with an embodiment of the present invention.

Nine pregelatinized and partially hydrolyzed starches prepared in accordance with embodiments of the present invention were prepared for various specific property tests (e.g., viscosity, flow, strength). The nine starches of the invention were tested with three commercially available starches.

A method for preparing pregelatinized and partially hydrolyzed starch according to the present invention, by mixing 100 kg of degermed corn flour commercially available from Bunge North America (St. Louis, MO) as CCM 260 Corn Meal, variation Aqueous aluminum sulfate precursors are prepared by substantially avoiding the weak acid and/or tartaric acid (less than 20% by weight of the total weak acid) chelated with calcium ions and varying amounts of water. The wet starch precursor was fed into a single screw extruder commercially available from American Extrusion International (South Beloit, IL) as Advantage 50. In the extruder, the wet starch precursor is pregelatinized and acid modified in a single step to allow it to proceed simultaneously.

Table 4 below describes the parameters for extruding corn flour in the presence of acid. The residence time of the extrusion (i.e., the time for pregelatinization and acid upgrading) is less than 30 seconds. All percentages are based on the total weight of the starch, except for the moisture expressed as the total wet weight of the sum of water, starch and other additives.

Conventional pregelatinized corn starch with a viscosity of 773 centipoise (designated as Composition 1A (comparative)) and commercially available as Clinton 277 (ADM, Chicago, IL) and Caliber 159 (Cargill, Wayzata, MN) Two low water demand starches (designated Composition 1B (comparative) and Composition 1C (comparative), respectively) prepared by squeezing acid modified corn starch were used to evaluate the resulting pregelatinized and partially hydrolyzed starch.

Pregelatinized and partially hydrolyzed starch was produced in an extrusion process designated as Composition 1D-1L.

Table 5 below details the various moisture and acid contents of the compositions 1D-1L for extrusion during extrusion. Compositions 1D-1H and 1L were prepared to have a moisture content of 16% by weight, and the two compositions 1I-1K were prepared to have a moisture content of 13% by weight. Compositions 1D-1G and Compositions 1I-1L were prepared in a liquid oxime in an amount ranging from 1% to 4% by weight, while Composition 1H included liquid hydrazine and tartaric acid. Compositions 1F and 1L were prepared using the same moisture content and acid, but in Example 3 there were different amounts of retarder.

The following Examples 2-4 test the various characteristics of the compositions described in Table 5. In Example 2, the viscosity of Composition 1B-1L in the continuous viscometer test was evaluated. Example 3 The flowability of a slurry prepared using one of Compositions 1A, 1D-1I, and 1K-1L was tested, which was evaluated by means of a collapse test. This data was then further confirmed by measuring the time of slurry hydration by 50%. This shows how much time it takes for the slurry to set. Example 4 Preparation of Test Compositions 1A, 1D-1I and 1K The strength of the slurry was evaluated by means of the compressive strength test described herein.

Example 2

This example illustrates the viscosity of a pre-gelatinized and partially hydrolyzed starch prepared in an extruder in accordance with an embodiment of the present invention. The composition 1D-1K is tested as compared to the extruded commercially available acid modified starch (Composition 1B-1C), specifically how the viscosity varies based on the amount of acid (eg, hydrazine) and moisture content, Moisture content is defined as the moisture level of the wetted starch fed through the extruder.

In the preparation for the test, the composition was mixed with water as a starch slurry such that the starch slurry contained the composition in an amount of 10% by weight. It should be noted that the term "solution" is used when the starch is completely gelatinized and completely dissolved, and the term "slurry" is used when the starch is not completely dissolved. The viscosity of each composition was then tested at various temperatures by the continuous viscometer technique described herein. The test results are plotted in Figures 1 and 2, which are used to evaluate pre-gelatinized and partially hydrolyzed starch by plotting viscosity (left y-axis) and temperature (right y-axis) versus time (x-axis). Continuous viscosity map of viscosity at different temperatures. The temperature curve covers each sample. The same temperature profile was used for each sample. Other curves show the viscosity of the starch.

The initial viscosity at 25 ° C is an indicator of the fluidity of the slurry system containing either of compositions 1B-1K. 25 ° C is the temperature at which the starch will be mixed with the stucco and other ingredients to make the board. In addition, at this temperature, the viscosity of the starch is inversely related to the fluidity of the mortar slurry.

The viscosity at the bottom (93 ° C) is an indicator of the molecular weight of either of Compositions 1B-1K. At a temperature of 93 ° C, the starch molecules are completely Dissolved in water. At 93 ° C, the viscosity of the starch solution is positively correlated with the molecular weight of the starch produced by partial hydrolysis.

Figure 1 is a graph showing the continuous viscosity of the viscosity (left y-axis) and temperature (right y-axis) over a 50-minute period (x-axis). Comparative compositions 1B and 1C and inventive compositions 1D-1H as described herein were mixed into the starch solution in an amount of 10% by weight based on the weight of the solution. To avoid the formation of agglomerates, starch was added to the water in a mixing cup of a Waring blender while mixing at low speed for 20 seconds. The starch solution was then evaluated using a Viscograph-E (C. W. Brabender® Instruments, Inc., South Hackensack, NJ). The viscosity is measured using a C.W. Brabender Viscograph (e.g., Viscograph-E using kinetic measurements using reaction torque) according to the Brabender viscosity measurement procedure as referred to herein. It should be noted that the Brabender unit is measured at a RPM of 75 using a sample cup size of 16 fluid ounces (about 500 cc) and a 700 cmg sleeve as defined herein. Those skilled in the art will also readily recognize that, as described therein, Brabender units can be converted to other viscosity measurements, such as centipoise (eg, when the equivalent measuring sleeve is 700 cmg, cP = BU x 2.1) ) or Krebs unit. A gluing profile of compositions 1D-1H and comparative compositions 1B and 1C extruded at 16% by weight moisture content is shown in FIG.

Considering the compositions 1D-1H of the present invention, as the enthalpy is increased from 1% by weight to 4% by weight, the initial viscosity is reduced from 70 Brabender units (BU) to 10BU, while the molecular weight is also reduced. The initial viscosity of compositions 1D-1H and the viscosity at 93 °C were reduced to as low as those of compositions 1B and 1C. Compositions 1B and 1C represent the conventional viscosity limits for low water demand starch.

The results of the compositions 1D-1H shown in Figure 1 can be shown in extrusion The best acid upgrade was achieved during the period. These results further demonstrate that the process of the present invention for preparing pregelatinized and partially hydrolyzed starch successfully reduces the viscosity (molecular weight) of the starch. No viscosity peak was observed between 70 ° C and 90 ° C indicating that the composition 1D-1H was completely gelatinized. If the composition 1D-1H is not fully gelled, there should be an increase in viscosity. Complete gelation of the starch composition was confirmed by differential scanning calorimetry (DSC).

Figure 2 is a second continuous viscosity plot for plotting viscosity (left y-axis) and temperature (right y-axis) over a 50 minute period (x-axis). Comparative Compositions 1B and 1C and all of the inventive compositions 1I-1K as described herein were mixed into the starch solution in an amount of 10% by weight based on the weight of the solution. To avoid the formation of agglomerates, starch was added to the water while mixing at low speed for 20 seconds in a mixing cup of a Waring blender. The starch solution was then evaluated using a Viscograph-E. The gluing profiles of compositions 1D-1H and comparative compositions 1B and 1C extruded at 13% by weight moisture content are shown in FIG.

A similar tendency to that observed with compositions 1D-1H was observed with compositions 1I-1K. In particular, the method of preparing pregelatinized and partially hydrolyzed starch in an extruder as described herein successfully reduced the viscosity of compositions 1I-1K.

As the enthalpy increased from 1% by weight to 3% by weight, the initial viscosity decreased from 75BU to 14BU, while the molecular weight also decreased. The initial viscosity of compositions 1I-1K and the viscosity at 93 °C were reduced to as low as those of compositions 1B and 1C.

Additionally, the results of compositions 1I-1K shown in Figure 2 demonstrate that optimal acid upgrading can be achieved during extrusion. No stickiness observed between 70 ° C and 90 ° C The peak value indicates that the composition 1I-1K is completely gelatinized.

In addition, these results show that at a given acid level, starch hydrolysis can be achieved at lower moisture levels than at higher moisture levels, because at lower moisture levels, there is more mechanical energy and Therefore more starch is degraded so that the starch will become smaller when the same acid level is used.

Example 3

This example illustrates the flowability of a gypsum slurry containing compositions 1A (comparative), 1D-1I, and 1K-1L. The collapse test is known to those skilled in the art to assess the fluidity of the composition.

In the test preparation, a water stucco ratio (WSR) of 100 was used, and each of the compositions 1A (comparative), 1D-1I, and 1K-1L was used in an amount of 2% by weight. The parameters outlined in Table 6 were used to prepare the slurry.

The starch is weighed into an anhydrous mixture comprising stucco and a heat resistant accelerator having a purity of more than 95%. Water, sodium trimetaphosphate (10% by weight solution), dispersant and retarder were weighed into a mixing tank of Hobart Mixer. The anhydrous mixture was poured into a mixing tank of a mixer available from the N505-Quart Mixer of Hobart (Troy, OH), immersed for 10 seconds and mixed at speed II for 30 seconds. For foam preparation, a 0.5% solution of Hyonic® PFM-33 soap (available from GEO® Specialty Chemicals, Ambler, PA) was formed and then mixed with air to make an air foam. Air foam is added to the slurry using a foam generator.

Each slurry was then placed in a cylinder having a diameter of 4.92 cm (1.95 in) and a height of 10 cm (3.94 in). The cylinder is then lifted to allow the slurry to flow freely. The diameter of the formed depression was then measured to account for the fluidity of the slurry and is reported in Table 7 below. Table 8 also includes the results of the 50% hydration time test explained in further detail below.

As can be observed from Table 7, the slurries prepared with compositions 1D-1I and 1K exhibited larger sizes than the slurries prepared with Composition 1A (comparative). It also solidified faster than Composition 1A (comparative), indicating that the slurry containing the 1D-1I and 1K compositions was more fluid than the slurry containing Composition 1A.

In addition, the 50% hydration time of the slurry was measured for the purpose of comparing the size of the collapse when the slurry was solidified at the same rate. Use a software profile that is generally known to those skilled in the art to measure the temperature of the slurry.

This additional test was conducted to confirm that the collapse test was correct, in particular, compared to composition 1A (comparative), observed with a slurry comprising pregelatinized and partially hydrolyzed starch prepared according to an embodiment of the invention. The larger fall is due to improved mobility rather than slow hydration.

Composition 1H prepared with 2% by weight hydrazine and 0.3% by weight tartaric acid effectively hydrolyzes the starch to a low viscosity and has a less impact on the hydration rate because tartaric acid and hydrazine have opposite effects on the hydration rate.

Figure 3 is a graph plotting temperature vs. time showing temperature rise solidification (TRS) hydration rate. The hydration rate of Composition 1F with 0.05% and 0.0625% retarder was faster or the same rate as Composition 1A (comparative), respectively.

As seen in Figure 3, the hydration rate of Composition 1L with 0.0625% by weight of retarder was the same as Composition 1A (comparative). The composition of the composition 1L having a 0.065% by weight retarder had a size of 18.415 cm (7 1/4 in), which was significantly larger than the composite 1A.

This result indicates that the larger the size of the collapse observed with the slurry comprising the pregelatinized and partially hydrolyzed starch prepared according to the examples of the present invention is Due to high fluidity rather than slower solidification. Furthermore, pregelatinized and partially hydrolyzed starch prepared in accordance with embodiments of the present invention will allow the panels to use less water without sacrificing fluidity.

Example 4

This example illustrates the strength of a gypsum wafer prepared from a slurry containing compositions 1A (comparative), 1D-1I, and 1K. The strength is assessed using the compressive strength test described herein.

In the preparation for the test, the slurry was prepared in an amount of 2% by weight with each of Compositions 1A (Comparative), 1D-1I and 1K-1L and using the parameters outlined in Table 4 above.

A gypsum wafer having a final density of 29 pcf was produced using a water-to-stucco ratio of 100 (WSR) and air foam. The starch is weighed into an anhydrous mixture comprising stucco and a heat resistant accelerator. Water, 10% sodium trimetaphosphate solution, dispersant and retarder were weighed into a mixing tank of Hobart Mixer. The anhydrous mixture was poured into a mixing tank of a mixer available from the N505-Quart Mixer of Hobart (Troy, OH), immersed for 10 seconds and mixed at speed II for 30 seconds. For foam preparation, a 0.5% solution of Hyonic® PFM-33 soap (available from GEO® Specialty Chemicals, Ambler, PA) was formed and then mixed with air to make an air foam. Air foam is added to the slurry using a foam generator. The foam generator was operated at a rate sufficient to achieve a desired plate density of 29 pcf. Immediately after the addition of the foam, the slurry was poured until it reached a point slightly above the top of the mold. Once the plaster solidifies, it scrapes off too much. The mold has been sprayed with a release agent (WD- ^40TM ). The wafer has a diameter of 10.16 cm (4 in) and a thickness of 1.27 cm (0.5 in).

After the wafer was hardened, the wafer was removed from the mold and then dried at 110 °F (43 °C) for 48 hours. After removal from the oven, the wafer was allowed to cool at room temperature for 1 hour. Using a material testing system available from MTS measurement of compressive strength to SATEC ^TM E / M Systems of commercially available Systems Corporation (Eden Prairie, Minnesota) . The load was applied continuously and without fluctuations at a rate of 0.04 吋/min (rate constant between 15 and 40 psi/s). The results are shown in Table 8 below.

As seen in Table 8, the compressive strength of the foamed discs containing compositions 1D-1I and 1K was comparable to that of Composition 1A (comparative), indicating pregelatinization and partially hydrolyzed starch without sacrificing its strength enhancing properties. Reduce the water demand in case. The desired compressive strength of the wafer sample was approximately 400 psi. Required The strength allows the board to be properly treated without breaking the board.

The terms "a" and "the" and "the" and "the" are used in the context of the present invention, especially in the context of the following claims, unless otherwise indicated herein. References (eg, related to acids, raw starch or other components or items) are to be construed as covering both singular and plural. Unless otherwise indicated herein or clearly contradicted by context, the use of the term "at least one" followed by a list of items (such as "at least one of A and B" (A and B)" shall be construed as meaning One item (A or B) of the listed items or any combination of two or more of the listed items (A and B). Unless otherwise stated, the terms "including", "having", "including" and "including" are to be construed as an open term (ie, meaning "including (but not limited to)"). The recitation of ranges of values herein are merely intended to serve as abbreviations to the individual values that are within the scope, and the individual values are incorporated in the specification, as if otherwise indicated herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by the context. The use of any and all examples of the embodiments of the invention, such as " Nothing in the specification should be construed as indicating that any element not claimed is essential to the practice of the invention.

Preferred embodiments of the invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of the preferred embodiments may become apparent to those skilled in the art after reading the foregoing description. The inventors expect that those skilled in the art will employ such changes as appropriate, and The inventors intend to practice the invention in a manner different from that specifically described herein. Accordingly, to the extent permitted by applicable law, the invention includes all modifications and equivalents of the subject matter described in the claims. In addition, the present invention encompasses any combination of the above-described elements in all possible variations thereof, unless otherwise indicated herein or otherwise clearly contradicted by the context.

Claims (10)

A method of making a pregelatinized and partially hydrolyzed starch comprising: (a) mixing at least water, non-pregelatinized starch, and substantially avoiding the weak acid of chelated calcium ions to produce a moisture content of about 8% by weight to About 25% by weight of the wet starch precursor; (b) feeding the wet starch precursor to an extruder; and (c) at about 150 ° C (about 300 ° F) to about 210 ° C in the extruder The moist starch is pregelatinized and acid modified at a mold temperature of (about 410 °F). The method of claim 1, wherein the weak acid that substantially prevents chelation of calcium ions comprises hydrazine. The method of claim 1 or 2, wherein tartaric acid is included in the mixing of the wet starch precursor. The method of any one of claims 1 to 3, wherein the method does not comprise a purification and neutralization step for pregelatinized and acid modified starch. A method of making a pregelatinized and partially hydrolyzed starch comprising: (a) mixing at least water, non-pregelatinized starch, and a strong acid to produce a moist starch precursor having a moisture content of from about 8 wt% to about 25 wt% Wherein the amount of the strong acid is about 0.05% by weight or less based on the weight of the starch; (b) feeding the moist starch precursor to an extruder; and (c) allowing the mold to be at a mold temperature of from about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F) in the extruder. The moist starch is pregelatinized and acid modified. The method of claim 5, wherein the strong acid has a pKa of about -1.7 or -1.7 or less. The method of claim 5, wherein the strong acid is sulfuric acid, nitric acid, hydrochloric acid or any combination thereof. A method of making a board comprising: (a) forming a pregelatinized and partially hydrolyzed starch by: (i) mixing at least water, non-pregelatinized starch, and an acid to form a moisture content of about 8% by weight. Up to about 25% by weight of a moist starch precursor selected from the group consisting of (1) a weak acid that substantially avoids chelation of calcium ions, (2) about 0.05% by weight or 0.05 weight by weight of the starch a strong acid in an amount of less than %, or (3) any combination thereof; (ii) feeding the wet starch precursor to an extruder; and (iii) having a temperature of about 150 ° C (about 300 ° F) to about The wet starch is pregelatinized and acid modified in the extruder at a temperature of 210 ° C (about 410 ° F); (b) the pregelatinized and partially hydrolyzed starch and at least water and Stucco mix Combining to form a slurry; (c) placing the slurry between a first cover sheet and a second cover sheet to form a wet pack; (d) cutting the wet pack into a sheet; and (e Dry the plate. The method of claim 8, wherein the slurry further comprises sodium trimetaphosphate. The method of claim 8 or claim 9, wherein the amount of water required to maintain the fluidity of the slurry at the same level as the slurry fluidity without pregelatinized and partially hydrolyzed starch is less than that in use. The amount of water required for pregelatinization and partial hydrolysis of starch prepared according to different methods is increased.